diff options
| author | Scott Rifenbark <scott.m.rifenbark@intel.com> | 2012-10-08 10:14:58 -0700 |
|---|---|---|
| committer | Richard Purdie <richard.purdie@linuxfoundation.org> | 2012-10-10 15:18:11 +0100 |
| commit | e0f0335467cc5bf1fedac8ac053d4565f1664ca1 (patch) | |
| tree | e84eb82d8ce84d7ba14866dc304b17e0f64d4240 /documentation | |
| parent | 274095d4c21a8f617a41f85a364db78e96f7bf4d (diff) | |
| download | poky-e0f0335467cc5bf1fedac8ac053d4565f1664ca1.tar.gz | |
documentation: dev-manual, bsp-guide - Removing/Moving Appendix A
The kernel example appendix is being removed. This broke a lot
of links. For now I have moved the information into a new section
called "Patching the Kernel". I have preserved the information
by adding the old appendix file as kerne-appendix-orig.xml.
(From yocto-docs rev: 994235a69362dfb0114ef9001ea7f2f2e2fdc5c3)
Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Diffstat (limited to 'documentation')
| -rw-r--r-- | documentation/bsp-guide/bsp.xml | 4 | ||||
| -rw-r--r-- | documentation/dev-manual/dev-manual-common-tasks.xml | 559 | ||||
| -rw-r--r-- | documentation/dev-manual/dev-manual-kernel-appendix-orig.xml | 553 | ||||
| -rw-r--r-- | documentation/dev-manual/dev-manual-model.xml | 21 | ||||
| -rw-r--r-- | documentation/dev-manual/dev-manual.xml | 2 |
5 files changed, 1124 insertions, 15 deletions
diff --git a/documentation/bsp-guide/bsp.xml b/documentation/bsp-guide/bsp.xml index 7c63e4f24d..2fa016a969 100644 --- a/documentation/bsp-guide/bsp.xml +++ b/documentation/bsp-guide/bsp.xml | |||
| @@ -618,10 +618,10 @@ | |||
| 618 | <filename>meta</filename> branch for your BSP. | 618 | <filename>meta</filename> branch for your BSP. |
| 619 | The configuration options will likely end up in that location anyway if the BSP gets | 619 | The configuration options will likely end up in that location anyway if the BSP gets |
| 620 | added to the Yocto Project. | 620 | added to the Yocto Project. |
| 621 | For a better understanding of working with a local clone of the kernel repository | 621 | <!-- For a better understanding of working with a local clone of the kernel repository |
| 622 | and a local bare clone of the kernel, see the | 622 | and a local bare clone of the kernel, see the |
| 623 | "<ulink url='&YOCTO_DOCS_DEV_URL;#modifying-the-kernel-source-code'>Modifying the Kernel | 623 | "<ulink url='&YOCTO_DOCS_DEV_URL;#modifying-the-kernel-source-code'>Modifying the Kernel |
| 624 | Source Code</ulink>" section also in the Yocto Project Development Manual. | 624 | Source Code</ulink>" section also in the Yocto Project Development Manual. --> |
| 625 | </para> | 625 | </para> |
| 626 | 626 | ||
| 627 | <para> | 627 | <para> |
diff --git a/documentation/dev-manual/dev-manual-common-tasks.xml b/documentation/dev-manual/dev-manual-common-tasks.xml index 918d884681..4ce0a94873 100644 --- a/documentation/dev-manual/dev-manual-common-tasks.xml +++ b/documentation/dev-manual/dev-manual-common-tasks.xml | |||
| @@ -1590,6 +1590,565 @@ | |||
| 1590 | </section> | 1590 | </section> |
| 1591 | </section> | 1591 | </section> |
| 1592 | 1592 | ||
| 1593 | |||
| 1594 | |||
| 1595 | |||
| 1596 | |||
| 1597 | |||
| 1598 | |||
| 1599 | |||
| 1600 | |||
| 1601 | |||
| 1602 | |||
| 1603 | |||
| 1604 | <section id="patching-the-kernel"> | ||
| 1605 | <title>Patching the Kernel</title> | ||
| 1606 | |||
| 1607 | <para> | ||
| 1608 | Kernel modification involves changing or adding configurations to an existing kernel, | ||
| 1609 | changing or adding recipes to the kernel that are needed to support specific hardware features, | ||
| 1610 | or even altering the source code itself. | ||
| 1611 | This appendix presents simple examples that modify the kernel source code, | ||
| 1612 | change the kernel configuration, and add a kernel source recipe. | ||
| 1613 | <note> | ||
| 1614 | You can use the <filename>yocto-kernel</filename> script | ||
| 1615 | found in the <link linkend='source-directory'>Source Directory</link> | ||
| 1616 | under <filename>scripts</filename> to manage kernel patches and configuration. | ||
| 1617 | See the "<ulink url='&YOCTO_DOCS_BSP_URL;#managing-kernel-patches-and-config-items-with-yocto-kernel'>Managing kernel Patches and Config Items with yocto-kernel</ulink>" | ||
| 1618 | section in the Yocto Project Board Support Packages (BSP) Developer's Guide for | ||
| 1619 | more information.</note> | ||
| 1620 | </para> | ||
| 1621 | |||
| 1622 | <para> | ||
| 1623 | This example adds some simple QEMU emulator console output at boot time by | ||
| 1624 | adding <filename>printk</filename> statements to the kernel's | ||
| 1625 | <filename>calibrate.c</filename> source code file. | ||
| 1626 | Booting the modified image causes the added messages to appear on the emulator's | ||
| 1627 | console. | ||
| 1628 | </para> | ||
| 1629 | |||
| 1630 | <section id='understanding-the-files-you-need'> | ||
| 1631 | <title>Understanding the Files You Need</title> | ||
| 1632 | |||
| 1633 | <para> | ||
| 1634 | Before you modify the kernel, you need to know what Git repositories and file | ||
| 1635 | structures you need. | ||
| 1636 | Briefly, you need the following: | ||
| 1637 | <itemizedlist> | ||
| 1638 | <listitem><para>A local | ||
| 1639 | <link linkend='source-directory'>Source Directory</link> for the | ||
| 1640 | poky Git repository</para></listitem> | ||
| 1641 | <listitem><para>Local copies of the | ||
| 1642 | <link linkend='poky-extras-repo'><filename>poky-extras</filename></link> | ||
| 1643 | Git repository placed within the Source Directory.</para></listitem> | ||
| 1644 | <listitem><para>A bare clone of the | ||
| 1645 | <link linkend='local-kernel-files'>Yocto Project Kernel</link> upstream Git | ||
| 1646 | repository to which you want to push your modifications. | ||
| 1647 | </para></listitem> | ||
| 1648 | <listitem><para>A copy of that bare clone in which you make your source | ||
| 1649 | modifications</para></listitem> | ||
| 1650 | </itemizedlist> | ||
| 1651 | </para> | ||
| 1652 | |||
| 1653 | <para> | ||
| 1654 | The following figure summarizes these four areas. | ||
| 1655 | Within each rectangular that represents a data structure, a | ||
| 1656 | host development directory pathname appears at the | ||
| 1657 | lower left-hand corner of the box. | ||
| 1658 | These pathnames are the locations used in this example. | ||
| 1659 | The figure also provides key statements and commands used during the kernel | ||
| 1660 | modification process: | ||
| 1661 | </para> | ||
| 1662 | |||
| 1663 | <para> | ||
| 1664 | <imagedata fileref="figures/kernel-example-repos-generic.png" width="7in" depth="5in" | ||
| 1665 | align="center" scale="100" /> | ||
| 1666 | </para> | ||
| 1667 | |||
| 1668 | <para> | ||
| 1669 | Here is a brief description of the four areas: | ||
| 1670 | <itemizedlist> | ||
| 1671 | <listitem><para><emphasis>Local Source Directory:</emphasis> | ||
| 1672 | This area contains all the metadata that supports building images | ||
| 1673 | using the OpenEmbedded build system. | ||
| 1674 | In this example, the | ||
| 1675 | <link linkend='source-directory'>Source Directory</link> also | ||
| 1676 | contains the | ||
| 1677 | <link linkend='build-directory'>Build Directory</link>, | ||
| 1678 | which contains the configuration directory | ||
| 1679 | that lets you control the build. | ||
| 1680 | Also in this example, the Source Directory contains local copies of the | ||
| 1681 | <filename>poky-extras</filename> Git repository.</para> | ||
| 1682 | <para>See the bulleted item | ||
| 1683 | "<link linkend='local-yp-release'>Yocto Project Release</link>" | ||
| 1684 | for information on how to get these files on your local system.</para></listitem> | ||
| 1685 | <listitem><para><emphasis>Local copies of the <filename>poky-extras</filename> Git Repository:</emphasis> | ||
| 1686 | This area contains the <filename>meta-kernel-dev</filename> layer, | ||
| 1687 | which is where you make changes that append the kernel build recipes. | ||
| 1688 | You edit <filename>.bbappend</filename> files to locate your | ||
| 1689 | local kernel source files and to identify the kernel being built. | ||
| 1690 | This Git repository is a gathering place for extensions to the Yocto Project | ||
| 1691 | (or really any) kernel recipes that faciliate the creation and development | ||
| 1692 | of kernel features, BSPs or configurations.</para> | ||
| 1693 | <para>See the bulleted item | ||
| 1694 | "<link linkend='poky-extras-repo'>The | ||
| 1695 | <filename>poky-extras</filename> Git Repository</link>" | ||
| 1696 | for information on how to get these files.</para></listitem> | ||
| 1697 | <listitem><para><emphasis>Bare Clone of the Yocto Project kernel:</emphasis> | ||
| 1698 | This bare Git repository tracks the upstream Git repository of the Linux | ||
| 1699 | Yocto kernel source code you are changing. | ||
| 1700 | When you modify the kernel you must work through a bare clone. | ||
| 1701 | All source code changes you make to the kernel must be committed and | ||
| 1702 | pushed to the bare clone using Git commands. | ||
| 1703 | As mentioned, the <filename>.bbappend</filename> file in the | ||
| 1704 | <filename>poky-extras</filename> repository points to the bare clone | ||
| 1705 | so that the build process can locate the locally changed source files.</para> | ||
| 1706 | <para>See the bulleted item | ||
| 1707 | "<link linkend='local-kernel-files'>Yocto Project Kernel</link>" | ||
| 1708 | for information on how to set up the bare clone. | ||
| 1709 | </para></listitem> | ||
| 1710 | <listitem><para><emphasis>Copy of the Yocto Project Kernel Bare Clone:</emphasis> | ||
| 1711 | This Git repository contains the actual source files that you modify. | ||
| 1712 | Any changes you make to files in this location need to ultimately be pushed | ||
| 1713 | to the bare clone using the <filename>git push</filename> command.</para> | ||
| 1714 | <para>See the bulleted item | ||
| 1715 | "<link linkend='local-kernel-files'>Yocto Project Kernel</link>" | ||
| 1716 | for information on how to set up the bare clone. | ||
| 1717 | <note>Typically, Git workflows follow a scheme where changes made to a local area | ||
| 1718 | are pulled into a Git repository. | ||
| 1719 | However, because the <filename>git pull</filename> command does not work | ||
| 1720 | with bare clones, this workflow pushes changes to the | ||
| 1721 | repository even though you could use other more complicated methods to | ||
| 1722 | get changes into the bare clone.</note> | ||
| 1723 | </para></listitem> | ||
| 1724 | </itemizedlist> | ||
| 1725 | </para> | ||
| 1726 | </section> | ||
| 1727 | |||
| 1728 | <section id='setting-up-the-local-yocto-project-files-git-repository'> | ||
| 1729 | <title>Setting Up the Local Source Directory</title> | ||
| 1730 | |||
| 1731 | <para> | ||
| 1732 | You can set up the | ||
| 1733 | <link linkend='source-directory'>Source Directory</link> | ||
| 1734 | through tarball extraction or by | ||
| 1735 | cloning the <filename>poky</filename> Git repository. | ||
| 1736 | This example uses <filename>poky</filename> as the root directory of the | ||
| 1737 | local Source Directory. | ||
| 1738 | See the bulleted item | ||
| 1739 | "<link linkend='local-yp-release'>Yocto Project Release</link>" | ||
| 1740 | for information on how to get these files. | ||
| 1741 | </para> | ||
| 1742 | |||
| 1743 | <para> | ||
| 1744 | Once you have Source Directory set up, | ||
| 1745 | you have many development branches from which you can work. | ||
| 1746 | From inside the local repository you can see the branch names and the tag names used | ||
| 1747 | in the upstream Git repository by using either of the following commands: | ||
| 1748 | <literallayout class='monospaced'> | ||
| 1749 | $ cd poky | ||
| 1750 | $ git branch -a | ||
| 1751 | $ git tag -l | ||
| 1752 | </literallayout> | ||
| 1753 | This example uses the Yocto Project &DISTRO; Release code named "&DISTRO_NAME;", | ||
| 1754 | which maps to the <filename>&DISTRO_NAME;</filename> branch in the repository. | ||
| 1755 | The following commands create and checkout the local <filename>&DISTRO_NAME;</filename> | ||
| 1756 | branch: | ||
| 1757 | <literallayout class='monospaced'> | ||
| 1758 | $ git checkout -b &DISTRO_NAME; origin/&DISTRO_NAME; | ||
| 1759 | Branch &DISTRO_NAME; set up to track remote branch &DISTRO_NAME; from origin. | ||
| 1760 | Switched to a new branch '&DISTRO_NAME;' | ||
| 1761 | </literallayout> | ||
| 1762 | </para> | ||
| 1763 | </section> | ||
| 1764 | |||
| 1765 | <section id='setting-up-the-poky-extras-git-repository'> | ||
| 1766 | <title>Setting Up the Local poky-extras Git Repository</title> | ||
| 1767 | |||
| 1768 | <para> | ||
| 1769 | This example creates a local copy of the <filename>poky-extras</filename> Git | ||
| 1770 | repository inside the <filename>poky</filename> Source Directory. | ||
| 1771 | See the bulleted item "<link linkend='poky-extras-repo'>The | ||
| 1772 | <filename>poky-extras</filename> Git Repository</link>" | ||
| 1773 | for information on how to set up a local copy of the | ||
| 1774 | <filename>poky-extras</filename> repository. | ||
| 1775 | </para> | ||
| 1776 | |||
| 1777 | <para> | ||
| 1778 | Because this example uses the Yocto Project &DISTRO; Release code | ||
| 1779 | named "&DISTRO_NAME;", which maps to the <filename>&DISTRO_NAME;</filename> | ||
| 1780 | branch in the repository, you need to be sure you are using that | ||
| 1781 | branch for <filename>poky-extras</filename>. | ||
| 1782 | The following commands create and checkout the local | ||
| 1783 | branch you are using for the <filename>&DISTRO_NAME;</filename> | ||
| 1784 | branch: | ||
| 1785 | <literallayout class='monospaced'> | ||
| 1786 | $ cd ~/poky/poky-extras | ||
| 1787 | $ git checkout -b &DISTRO_NAME; origin/&DISTRO_NAME; | ||
| 1788 | Branch &DISTRO_NAME; set up to track remote branch &DISTRO_NAME; from origin. | ||
| 1789 | Switched to a new branch '&DISTRO_NAME;' | ||
| 1790 | </literallayout> | ||
| 1791 | </para> | ||
| 1792 | </section> | ||
| 1793 | |||
| 1794 | <section id='setting-up-the-bare-clone-and-its-copy'> | ||
| 1795 | <title>Setting Up the Bare Clone and its Copy</title> | ||
| 1796 | |||
| 1797 | <para> | ||
| 1798 | This example modifies the <filename>linux-yocto-3.4</filename> kernel. | ||
| 1799 | Thus, you need to create a bare clone of that kernel and then make a copy of the | ||
| 1800 | bare clone. | ||
| 1801 | See the bulleted item | ||
| 1802 | "<link linkend='local-kernel-files'>Yocto Project Kernel</link>" | ||
| 1803 | for information on how to do that. | ||
| 1804 | </para> | ||
| 1805 | |||
| 1806 | <para> | ||
| 1807 | The bare clone exists for the kernel build tools and simply as the receiving end | ||
| 1808 | of <filename>git push</filename> | ||
| 1809 | commands after you make edits and commits inside the copy of the clone. | ||
| 1810 | The copy (<filename>my-linux-yocto-3.4-work</filename> in this example) has to have | ||
| 1811 | a local branch created and checked out for your work. | ||
| 1812 | This example uses <filename>common-pc-base</filename> as the local branch. | ||
| 1813 | The following commands create and checkout the branch: | ||
| 1814 | <literallayout class='monospaced'> | ||
| 1815 | $ cd ~/my-linux-yocto-3.4-work | ||
| 1816 | $ git checkout -b standard-common-pc-base origin/standard/common-pc/base | ||
| 1817 | Branch standard-common-pc-base set up to track remote branch | ||
| 1818 | standard/common-pc/base from origin. | ||
| 1819 | Switched to a new branch 'standard-common-pc-base' | ||
| 1820 | </literallayout> | ||
| 1821 | </para> | ||
| 1822 | </section> | ||
| 1823 | |||
| 1824 | <section id='building-and-booting-the-default-qemu-kernel-image'> | ||
| 1825 | <title>Building and Booting the Default QEMU Kernel Image</title> | ||
| 1826 | |||
| 1827 | <para> | ||
| 1828 | Before we make changes to the kernel source files, this example first builds the | ||
| 1829 | default image and then boots it inside the QEMU emulator. | ||
| 1830 | <note> | ||
| 1831 | Because a full build can take hours, you should check two variables in the | ||
| 1832 | <filename>build</filename> directory that is created after you source the | ||
| 1833 | <filename>&OE_INIT_FILE;</filename> script. | ||
| 1834 | You can find these variables | ||
| 1835 | <filename>BB_NUMBER_THREADS</filename> and <filename>PARALLEL_MAKE</filename> | ||
| 1836 | in the <filename>build/conf</filename> directory in the | ||
| 1837 | <filename>local.conf</filename> configuration file. | ||
| 1838 | By default, these variables are commented out. | ||
| 1839 | If your host development system supports multi-core and multi-thread capabilities, | ||
| 1840 | you can uncomment these statements and set the variables to significantly shorten | ||
| 1841 | the full build time. | ||
| 1842 | As a guideline, set both <filename>BB_NUMBER_THREADS</filename> and | ||
| 1843 | <filename>PARALLEL_MAKE</filename> to twice the number | ||
| 1844 | of cores your machine supports. | ||
| 1845 | </note> | ||
| 1846 | The following two commands <filename>source</filename> the build environment setup script | ||
| 1847 | and build the default <filename>qemux86</filename> image. | ||
| 1848 | If necessary, the script creates the build directory: | ||
| 1849 | <literallayout class='monospaced'> | ||
| 1850 | $ cd ~/poky | ||
| 1851 | $ source &OE_INIT_FILE; | ||
| 1852 | You had no conf/local.conf file. This configuration file has therefore been | ||
| 1853 | created for you with some default values. You may wish to edit it to use a | ||
| 1854 | different MACHINE (target hardware) or enable parallel build options to take | ||
| 1855 | advantage of multiple cores for example. See the file for more information as | ||
| 1856 | common configuration options are commented. | ||
| 1857 | |||
| 1858 | The Yocto Project has extensive documentation about OE including a reference manual | ||
| 1859 | which can be found at: | ||
| 1860 | http://yoctoproject.org/documentation | ||
| 1861 | |||
| 1862 | For more information about OpenEmbedded see their website: | ||
| 1863 | http://www.openembedded.org/ | ||
| 1864 | |||
| 1865 | You had no conf/bblayers.conf file. The configuration file has been created for | ||
| 1866 | you with some default values. To add additional metadata layers into your | ||
| 1867 | configuration please add entries to this file. | ||
| 1868 | |||
| 1869 | The Yocto Project has extensive documentation about OE including a reference manual | ||
| 1870 | which can be found at: | ||
| 1871 | http://yoctoproject.org/documentation | ||
| 1872 | |||
| 1873 | For more information about OpenEmbedded see their website: | ||
| 1874 | http://www.openembedded.org/ | ||
| 1875 | |||
| 1876 | |||
| 1877 | |||
| 1878 | ### Shell environment set up for builds. ### | ||
| 1879 | |||
| 1880 | You can now run 'bitbake <target>>' | ||
| 1881 | |||
| 1882 | Common targets are: | ||
| 1883 | core-image-minimal | ||
| 1884 | core-image-sato | ||
| 1885 | meta-toolchain | ||
| 1886 | meta-toolchain-sdk | ||
| 1887 | adt-installer | ||
| 1888 | meta-ide-support | ||
| 1889 | |||
| 1890 | You can also run generated qemu images with a command like 'runqemu qemux86' | ||
| 1891 | </literallayout> | ||
| 1892 | </para> | ||
| 1893 | |||
| 1894 | <para> | ||
| 1895 | The following <filename>bitbake</filename> command starts the build: | ||
| 1896 | <literallayout class='monospaced'> | ||
| 1897 | $ bitbake -k core-image-minimal | ||
| 1898 | </literallayout> | ||
| 1899 | <note>Be sure to check the settings in the <filename>local.conf</filename> | ||
| 1900 | before starting the build.</note> | ||
| 1901 | </para> | ||
| 1902 | |||
| 1903 | <para> | ||
| 1904 | After the build completes, you can start the QEMU emulator using the resulting image | ||
| 1905 | <filename>qemux86</filename> as follows: | ||
| 1906 | <literallayout class='monospaced'> | ||
| 1907 | $ runqemu qemux86 | ||
| 1908 | </literallayout> | ||
| 1909 | </para> | ||
| 1910 | |||
| 1911 | <para> | ||
| 1912 | As the image boots in the emulator, console message and status output appears | ||
| 1913 | across the terminal window. | ||
| 1914 | Because the output scrolls by quickly, it is difficult to read. | ||
| 1915 | To examine the output, you log into the system using the | ||
| 1916 | login <filename>root</filename> with no password. | ||
| 1917 | Once you are logged in, issue the following command to scroll through the | ||
| 1918 | console output: | ||
| 1919 | <literallayout class='monospaced'> | ||
| 1920 | # dmesg | less | ||
| 1921 | </literallayout> | ||
| 1922 | </para> | ||
| 1923 | |||
| 1924 | <para> | ||
| 1925 | Take note of the output as you will want to look for your inserted print command output | ||
| 1926 | later in the example. | ||
| 1927 | </para> | ||
| 1928 | </section> | ||
| 1929 | |||
| 1930 | <section id='changing-the-source-code-and-pushing-it-to-the-bare-clone'> | ||
| 1931 | <title>Changing the Source Code and Pushing it to the Bare Clone</title> | ||
| 1932 | |||
| 1933 | <para> | ||
| 1934 | The file you change in this example is named <filename>calibrate.c</filename> | ||
| 1935 | and is located in the <filename>my-linux-yocto-3.4-work</filename> Git repository | ||
| 1936 | (the copy of the bare clone) in <filename>init</filename>. | ||
| 1937 | This example simply inserts several <filename>printk</filename> statements | ||
| 1938 | at the beginning of the <filename>calibrate_delay</filename> function. | ||
| 1939 | </para> | ||
| 1940 | |||
| 1941 | <para> | ||
| 1942 | Here is the unaltered code at the start of this function: | ||
| 1943 | <literallayout class='monospaced'> | ||
| 1944 | void __cpuinit calibrate_delay(void) | ||
| 1945 | { | ||
| 1946 | unsigned long lpj; | ||
| 1947 | static bool printed; | ||
| 1948 | int this_cpu = smp_processor_id(); | ||
| 1949 | |||
| 1950 | if (per_cpu(cpu_loops_per_jiffy, this_cpu)) { | ||
| 1951 | . | ||
| 1952 | . | ||
| 1953 | . | ||
| 1954 | </literallayout> | ||
| 1955 | </para> | ||
| 1956 | |||
| 1957 | <para> | ||
| 1958 | Here is the altered code showing five new <filename>printk</filename> statements | ||
| 1959 | near the top of the function: | ||
| 1960 | <literallayout class='monospaced'> | ||
| 1961 | void __cpuinit calibrate_delay(void) | ||
| 1962 | { | ||
| 1963 | unsigned long lpj; | ||
| 1964 | static bool printed; | ||
| 1965 | int this_cpu = smp_processor_id(); | ||
| 1966 | |||
| 1967 | printk("*************************************\n"); | ||
| 1968 | printk("* *\n"); | ||
| 1969 | printk("* HELLO YOCTO KERNEL *\n"); | ||
| 1970 | printk("* *\n"); | ||
| 1971 | printk("*************************************\n"); | ||
| 1972 | |||
| 1973 | if (per_cpu(cpu_loops_per_jiffy, this_cpu)) { | ||
| 1974 | . | ||
| 1975 | . | ||
| 1976 | . | ||
| 1977 | </literallayout> | ||
| 1978 | </para> | ||
| 1979 | |||
| 1980 | <para> | ||
| 1981 | After making and saving your changes, you need to stage them for the push. | ||
| 1982 | The following Git commands are one method of staging and committing your changes: | ||
| 1983 | <literallayout class='monospaced'> | ||
| 1984 | $ git add calibrate.c | ||
| 1985 | $ git commit --signoff | ||
| 1986 | </literallayout> | ||
| 1987 | </para> | ||
| 1988 | |||
| 1989 | <para> | ||
| 1990 | Once the source code has been modified, you need to use Git to push the changes to | ||
| 1991 | the bare clone. | ||
| 1992 | If you do not push the changes, then the OpenEmbedded build system will not pick | ||
| 1993 | up the changed source files. | ||
| 1994 | </para> | ||
| 1995 | |||
| 1996 | <para> | ||
| 1997 | The following command pushes the changes to the bare clone: | ||
| 1998 | <literallayout class='monospaced'> | ||
| 1999 | $ git push origin standard-common-pc-base:standard/default/common-pc/base | ||
| 2000 | </literallayout> | ||
| 2001 | </para> | ||
| 2002 | </section> | ||
| 2003 | |||
| 2004 | <section id='changing-build-parameters-for-your-build'> | ||
| 2005 | <title>Changing Build Parameters for Your Build</title> | ||
| 2006 | |||
| 2007 | <para> | ||
| 2008 | At this point, the source has been changed and pushed. | ||
| 2009 | The example now defines some variables used by the OpenEmbedded build system | ||
| 2010 | to locate your kernel source. | ||
| 2011 | You essentially need to identify where to find the kernel recipe and the changed source code. | ||
| 2012 | You also need to be sure some basic configurations are in place that identify the | ||
| 2013 | type of machine you are building and to help speed up the build should your host support | ||
| 2014 | multiple-core and thread capabilities. | ||
| 2015 | </para> | ||
| 2016 | |||
| 2017 | <para> | ||
| 2018 | Do the following to make sure the build parameters are set up for the example. | ||
| 2019 | Once you set up these build parameters, they do not have to change unless you | ||
| 2020 | change the target architecture of the machine you are building or you move | ||
| 2021 | the bare clone, copy of the clone, or the <filename>poky-extras</filename> repository: | ||
| 2022 | <itemizedlist> | ||
| 2023 | <listitem><para><emphasis>Build for the Correct Target Architecture:</emphasis> The | ||
| 2024 | <filename>local.conf</filename> file in the build directory defines the build's | ||
| 2025 | target architecture. | ||
| 2026 | By default, <filename>MACHINE</filename> is set to | ||
| 2027 | <filename>qemux86</filename>, which specifies a 32-bit | ||
| 2028 | <trademark class='registered'>Intel</trademark> Architecture | ||
| 2029 | target machine suitable for the QEMU emulator. | ||
| 2030 | In this example, <filename>MACHINE</filename> is correctly configured. | ||
| 2031 | </para></listitem> | ||
| 2032 | <listitem><para><emphasis>Optimize Build Time:</emphasis> Also in the | ||
| 2033 | <filename>local.conf</filename> file are two variables that can speed your | ||
| 2034 | build time if your host supports multi-core and multi-thread capabilities: | ||
| 2035 | <filename>BB_NUMBER_THREADS</filename> and <filename>PARALLEL_MAKE</filename>. | ||
| 2036 | If the host system has multiple cores then you can optimize build time | ||
| 2037 | by setting both these variables to twice the number of | ||
| 2038 | cores.</para></listitem> | ||
| 2039 | <listitem><para><emphasis>Identify Your <filename>meta-kernel-dev</filename> | ||
| 2040 | Layer:</emphasis> The <filename>BBLAYERS</filename> variable in the | ||
| 2041 | <filename>bblayers.conf</filename> file found in the | ||
| 2042 | <filename>poky/build/conf</filename> directory needs to have the path to your local | ||
| 2043 | <filename>meta-kernel-dev</filename> layer. | ||
| 2044 | By default, the <filename>BBLAYERS</filename> variable contains paths to | ||
| 2045 | <filename>meta</filename> and <filename>meta-yocto</filename> in the | ||
| 2046 | <filename>poky</filename> Git repository. | ||
| 2047 | Add the path to your <filename>meta-kernel-dev</filename> location. | ||
| 2048 | Be sure to substitute your user information in the statement. | ||
| 2049 | Here is an example: | ||
| 2050 | <literallayout class='monospaced'> | ||
| 2051 | BBLAYERS = " \ | ||
| 2052 | /home/scottrif/poky/meta \ | ||
| 2053 | /home/scottrif/poky/meta-yocto \ | ||
| 2054 | /home/scottrif/poky/meta-yocto-bsp \ | ||
| 2055 | /home/scottrif/poky/poky-extras/meta-kernel-dev \ | ||
| 2056 | " | ||
| 2057 | </literallayout></para></listitem> | ||
| 2058 | <listitem><para><emphasis>Identify Your Source Files:</emphasis> In the | ||
| 2059 | <filename>linux-yocto_3.4.bbappend</filename> file located in the | ||
| 2060 | <filename>poky-extras/meta-kernel-dev/recipes-kernel/linux</filename> | ||
| 2061 | directory, you need to identify the location of the | ||
| 2062 | local source code, which in this example is the bare clone named | ||
| 2063 | <filename>linux-yocto-3.4.git</filename>. | ||
| 2064 | To do this, set the <filename>KSRC_linux_yocto</filename> variable to point to your | ||
| 2065 | local <filename>linux-yocto-3.4.git</filename> Git repository by adding the | ||
| 2066 | following statement. | ||
| 2067 | Also, be sure the <filename>SRC_URI</filename> variable is pointing to | ||
| 2068 | your kernel source files by removing the comment. | ||
| 2069 | Finally, be sure to substitute your user information in the statement: | ||
| 2070 | <literallayout class='monospaced'> | ||
| 2071 | KSRC_linux_yocto_3_4 ?= "/home/scottrif/linux-yocto-3.4.git" | ||
| 2072 | SRC_URI = "git://${KSRC_linux_yocto_3_4};protocol=file;nocheckout=1;branch=${KBRANCH},meta;name=machine,meta" | ||
| 2073 | </literallayout></para></listitem> | ||
| 2074 | </itemizedlist> | ||
| 2075 | </para> | ||
| 2076 | |||
| 2077 | <note> | ||
| 2078 | <para>Before attempting to build the modified kernel, there is one more set of changes you | ||
| 2079 | need to make in the <filename>meta-kernel-dev</filename> layer. | ||
| 2080 | Because all the kernel <filename>.bbappend</filename> files are parsed during the | ||
| 2081 | build process regardless of whether you are using them or not, you should either | ||
| 2082 | comment out the <filename>COMPATIBLE_MACHINE</filename> statements in all | ||
| 2083 | unused <filename>.bbappend</filename> files, or simply remove (or rename) all the files | ||
| 2084 | except the one your are using for the build | ||
| 2085 | (i.e. <filename>linux-yocto_3.4.bbappend</filename> in this example).</para> | ||
| 2086 | <para>If you do not make one of these two adjustments, your machine will be compatible | ||
| 2087 | with all the kernel recipes in the <filename>meta-kernel-dev</filename> layer. | ||
| 2088 | When your machine is comapatible with all the kernel recipes, the build attempts | ||
| 2089 | to build all kernels in the layer. | ||
| 2090 | You could end up with build errors blocking your work.</para> | ||
| 2091 | </note> | ||
| 2092 | </section> | ||
| 2093 | |||
| 2094 | <section id='building-and-booting-the-modified-qemu-kernel-image'> | ||
| 2095 | <title>Building and Booting the Modified QEMU Kernel Image</title> | ||
| 2096 | |||
| 2097 | <para> | ||
| 2098 | Next, you need to build the modified image. | ||
| 2099 | Do the following: | ||
| 2100 | <orderedlist> | ||
| 2101 | <listitem><para>Your environment should be set up since you previously sourced | ||
| 2102 | the <filename>&OE_INIT_FILE;</filename> script. | ||
| 2103 | If it isn't, source the script again from <filename>poky</filename>. | ||
| 2104 | <literallayout class='monospaced'> | ||
| 2105 | $ cd ~/poky | ||
| 2106 | $ source &OE_INIT_FILE; | ||
| 2107 | </literallayout> | ||
| 2108 | </para></listitem> | ||
| 2109 | <listitem><para>Be sure old images are cleaned out by running the | ||
| 2110 | <filename>cleanall</filename> BitBake task as follows from your build directory: | ||
| 2111 | <literallayout class='monospaced'> | ||
| 2112 | $ bitbake -c cleanall linux-yocto | ||
| 2113 | </literallayout></para> | ||
| 2114 | <para><note>Never remove any files by hand from the <filename>tmp/deploy</filename> | ||
| 2115 | directory insided the build directory. | ||
| 2116 | Always use the BitBake <filename>cleanall</filename> task to clear | ||
| 2117 | out previous builds.</note></para></listitem> | ||
| 2118 | <listitem><para>Next, build the kernel image using this command: | ||
| 2119 | <literallayout class='monospaced'> | ||
| 2120 | $ bitbake -k core-image-minimal | ||
| 2121 | </literallayout></para></listitem> | ||
| 2122 | <listitem><para>Finally, boot the modified image in the QEMU emulator | ||
| 2123 | using this command: | ||
| 2124 | <literallayout class='monospaced'> | ||
| 2125 | $ runqemu qemux86 | ||
| 2126 | </literallayout></para></listitem> | ||
| 2127 | </orderedlist> | ||
| 2128 | </para> | ||
| 2129 | |||
| 2130 | <para> | ||
| 2131 | Log into the machine using <filename>root</filename> with no password and then | ||
| 2132 | use the following shell command to scroll through the console's boot output. | ||
| 2133 | <literallayout class='monospaced'> | ||
| 2134 | # dmesg | less | ||
| 2135 | </literallayout> | ||
| 2136 | </para> | ||
| 2137 | |||
| 2138 | <para> | ||
| 2139 | You should see the results of your <filename>printk</filename> statements | ||
| 2140 | as part of the output. | ||
| 2141 | </para> | ||
| 2142 | </section> | ||
| 2143 | </section> | ||
| 2144 | |||
| 2145 | |||
| 2146 | |||
| 2147 | |||
| 2148 | |||
| 2149 | |||
| 2150 | |||
| 2151 | |||
| 1593 | <section id="usingpoky-changes-updatingimages"> | 2152 | <section id="usingpoky-changes-updatingimages"> |
| 1594 | <title>Updating Existing Images</title> | 2153 | <title>Updating Existing Images</title> |
| 1595 | 2154 | ||
diff --git a/documentation/dev-manual/dev-manual-kernel-appendix-orig.xml b/documentation/dev-manual/dev-manual-kernel-appendix-orig.xml new file mode 100644 index 0000000000..6ea77d030c --- /dev/null +++ b/documentation/dev-manual/dev-manual-kernel-appendix-orig.xml | |||
| @@ -0,0 +1,553 @@ | |||
| 1 | <!DOCTYPE appendix PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" | ||
| 2 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" | ||
| 3 | [<!ENTITY % poky SYSTEM "../poky.ent"> %poky; ] > | ||
| 4 | |||
| 5 | <appendix id='dev-manual-kernel-appendix'> | ||
| 6 | |||
| 7 | <title>Kernel Modification Example</title> | ||
| 8 | |||
| 9 | <para> | ||
| 10 | Kernel modification involves changing or adding configurations to an existing kernel, | ||
| 11 | changing or adding recipes to the kernel that are needed to support specific hardware features, | ||
| 12 | or even altering the source code itself. | ||
| 13 | This appendix presents simple examples that modify the kernel source code, | ||
| 14 | change the kernel configuration, and add a kernel source recipe. | ||
| 15 | <note> | ||
| 16 | You can use the <filename>yocto-kernel</filename> script | ||
| 17 | found in the <link linkend='source-directory'>Source Directory</link> | ||
| 18 | under <filename>scripts</filename> to manage kernel patches and configuration. | ||
| 19 | See the "<ulink url='&YOCTO_DOCS_BSP_URL;#managing-kernel-patches-and-config-items-with-yocto-kernel'>Managing kernel Patches and Config Items with yocto-kernel</ulink>" | ||
| 20 | section in the Yocto Project Board Support Packages (BSP) Developer's Guide for | ||
| 21 | more information.</note> | ||
| 22 | </para> | ||
| 23 | |||
| 24 | <section id='modifying-the-kernel-source-code'> | ||
| 25 | <title>Modifying the Kernel Source Code</title> | ||
| 26 | |||
| 27 | <para> | ||
| 28 | This example adds some simple QEMU emulator console output at boot time by | ||
| 29 | adding <filename>printk</filename> statements to the kernel's | ||
| 30 | <filename>calibrate.c</filename> source code file. | ||
| 31 | Booting the modified image causes the added messages to appear on the emulator's | ||
| 32 | console. | ||
| 33 | </para> | ||
| 34 | |||
| 35 | <section id='understanding-the-files-you-need'> | ||
| 36 | <title>Understanding the Files You Need</title> | ||
| 37 | |||
| 38 | <para> | ||
| 39 | Before you modify the kernel, you need to know what Git repositories and file | ||
| 40 | structures you need. | ||
| 41 | Briefly, you need the following: | ||
| 42 | <itemizedlist> | ||
| 43 | <listitem><para>A local | ||
| 44 | <link linkend='source-directory'>Source Directory</link> for the | ||
| 45 | poky Git repository</para></listitem> | ||
| 46 | <listitem><para>Local copies of the | ||
| 47 | <link linkend='poky-extras-repo'><filename>poky-extras</filename></link> | ||
| 48 | Git repository placed within the Source Directory.</para></listitem> | ||
| 49 | <listitem><para>A bare clone of the | ||
| 50 | <link linkend='local-kernel-files'>Yocto Project Kernel</link> upstream Git | ||
| 51 | repository to which you want to push your modifications. | ||
| 52 | </para></listitem> | ||
| 53 | <listitem><para>A copy of that bare clone in which you make your source | ||
| 54 | modifications</para></listitem> | ||
| 55 | </itemizedlist> | ||
| 56 | </para> | ||
| 57 | |||
| 58 | <para> | ||
| 59 | The following figure summarizes these four areas. | ||
| 60 | Within each rectangular that represents a data structure, a | ||
| 61 | host development directory pathname appears at the | ||
| 62 | lower left-hand corner of the box. | ||
| 63 | These pathnames are the locations used in this example. | ||
| 64 | The figure also provides key statements and commands used during the kernel | ||
| 65 | modification process: | ||
| 66 | </para> | ||
| 67 | |||
| 68 | <para> | ||
| 69 | <imagedata fileref="figures/kernel-example-repos-generic.png" width="7in" depth="5in" | ||
| 70 | align="center" scale="100" /> | ||
| 71 | </para> | ||
| 72 | |||
| 73 | <para> | ||
| 74 | Here is a brief description of the four areas: | ||
| 75 | <itemizedlist> | ||
| 76 | <listitem><para><emphasis>Local Source Directory:</emphasis> | ||
| 77 | This area contains all the metadata that supports building images | ||
| 78 | using the OpenEmbedded build system. | ||
| 79 | In this example, the | ||
| 80 | <link linkend='source-directory'>Source Directory</link> also | ||
| 81 | contains the | ||
| 82 | <link linkend='build-directory'>Build Directory</link>, | ||
| 83 | which contains the configuration directory | ||
| 84 | that lets you control the build. | ||
| 85 | Also in this example, the Source Directory contains local copies of the | ||
| 86 | <filename>poky-extras</filename> Git repository.</para> | ||
| 87 | <para>See the bulleted item | ||
| 88 | "<link linkend='local-yp-release'>Yocto Project Release</link>" | ||
| 89 | for information on how to get these files on your local system.</para></listitem> | ||
| 90 | <listitem><para><emphasis>Local copies of the <filename>poky-extras</filename> Git Repository:</emphasis> | ||
| 91 | This area contains the <filename>meta-kernel-dev</filename> layer, | ||
| 92 | which is where you make changes that append the kernel build recipes. | ||
| 93 | You edit <filename>.bbappend</filename> files to locate your | ||
| 94 | local kernel source files and to identify the kernel being built. | ||
| 95 | This Git repository is a gathering place for extensions to the Yocto Project | ||
| 96 | (or really any) kernel recipes that faciliate the creation and development | ||
| 97 | of kernel features, BSPs or configurations.</para> | ||
| 98 | <para>See the bulleted item | ||
| 99 | "<link linkend='poky-extras-repo'>The | ||
| 100 | <filename>poky-extras</filename> Git Repository</link>" | ||
| 101 | for information on how to get these files.</para></listitem> | ||
| 102 | <listitem><para><emphasis>Bare Clone of the Yocto Project kernel:</emphasis> | ||
| 103 | This bare Git repository tracks the upstream Git repository of the Linux | ||
| 104 | Yocto kernel source code you are changing. | ||
| 105 | When you modify the kernel you must work through a bare clone. | ||
| 106 | All source code changes you make to the kernel must be committed and | ||
| 107 | pushed to the bare clone using Git commands. | ||
| 108 | As mentioned, the <filename>.bbappend</filename> file in the | ||
| 109 | <filename>poky-extras</filename> repository points to the bare clone | ||
| 110 | so that the build process can locate the locally changed source files.</para> | ||
| 111 | <para>See the bulleted item | ||
| 112 | "<link linkend='local-kernel-files'>Yocto Project Kernel</link>" | ||
| 113 | for information on how to set up the bare clone. | ||
| 114 | </para></listitem> | ||
| 115 | <listitem><para><emphasis>Copy of the Yocto Project Kernel Bare Clone:</emphasis> | ||
| 116 | This Git repository contains the actual source files that you modify. | ||
| 117 | Any changes you make to files in this location need to ultimately be pushed | ||
| 118 | to the bare clone using the <filename>git push</filename> command.</para> | ||
| 119 | <para>See the bulleted item | ||
| 120 | "<link linkend='local-kernel-files'>Yocto Project Kernel</link>" | ||
| 121 | for information on how to set up the bare clone. | ||
| 122 | <note>Typically, Git workflows follow a scheme where changes made to a local area | ||
| 123 | are pulled into a Git repository. | ||
| 124 | However, because the <filename>git pull</filename> command does not work | ||
| 125 | with bare clones, this workflow pushes changes to the | ||
| 126 | repository even though you could use other more complicated methods to | ||
| 127 | get changes into the bare clone.</note> | ||
| 128 | </para></listitem> | ||
| 129 | </itemizedlist> | ||
| 130 | </para> | ||
| 131 | </section> | ||
| 132 | |||
| 133 | <section id='setting-up-the-local-yocto-project-files-git-repository'> | ||
| 134 | <title>Setting Up the Local Source Directory</title> | ||
| 135 | |||
| 136 | <para> | ||
| 137 | You can set up the | ||
| 138 | <link linkend='source-directory'>Source Directory</link> | ||
| 139 | through tarball extraction or by | ||
| 140 | cloning the <filename>poky</filename> Git repository. | ||
| 141 | This example uses <filename>poky</filename> as the root directory of the | ||
| 142 | local Source Directory. | ||
| 143 | See the bulleted item | ||
| 144 | "<link linkend='local-yp-release'>Yocto Project Release</link>" | ||
| 145 | for information on how to get these files. | ||
| 146 | </para> | ||
| 147 | |||
| 148 | <para> | ||
| 149 | Once you have Source Directory set up, | ||
| 150 | you have many development branches from which you can work. | ||
| 151 | From inside the local repository you can see the branch names and the tag names used | ||
| 152 | in the upstream Git repository by using either of the following commands: | ||
| 153 | <literallayout class='monospaced'> | ||
| 154 | $ cd poky | ||
| 155 | $ git branch -a | ||
| 156 | $ git tag -l | ||
| 157 | </literallayout> | ||
| 158 | This example uses the Yocto Project &DISTRO; Release code named "&DISTRO_NAME;", | ||
| 159 | which maps to the <filename>&DISTRO_NAME;</filename> branch in the repository. | ||
| 160 | The following commands create and checkout the local <filename>&DISTRO_NAME;</filename> | ||
| 161 | branch: | ||
| 162 | <literallayout class='monospaced'> | ||
| 163 | $ git checkout -b &DISTRO_NAME; origin/&DISTRO_NAME; | ||
| 164 | Branch &DISTRO_NAME; set up to track remote branch &DISTRO_NAME; from origin. | ||
| 165 | Switched to a new branch '&DISTRO_NAME;' | ||
| 166 | </literallayout> | ||
| 167 | </para> | ||
| 168 | </section> | ||
| 169 | |||
| 170 | <section id='setting-up-the-poky-extras-git-repository'> | ||
| 171 | <title>Setting Up the Local poky-extras Git Repository</title> | ||
| 172 | |||
| 173 | <para> | ||
| 174 | This example creates a local copy of the <filename>poky-extras</filename> Git | ||
| 175 | repository inside the <filename>poky</filename> Source Directory. | ||
| 176 | See the bulleted item "<link linkend='poky-extras-repo'>The | ||
| 177 | <filename>poky-extras</filename> Git Repository</link>" | ||
| 178 | for information on how to set up a local copy of the | ||
| 179 | <filename>poky-extras</filename> repository. | ||
| 180 | </para> | ||
| 181 | |||
| 182 | <para> | ||
| 183 | Because this example uses the Yocto Project &DISTRO; Release code | ||
| 184 | named "&DISTRO_NAME;", which maps to the <filename>&DISTRO_NAME;</filename> | ||
| 185 | branch in the repository, you need to be sure you are using that | ||
| 186 | branch for <filename>poky-extras</filename>. | ||
| 187 | The following commands create and checkout the local | ||
| 188 | branch you are using for the <filename>&DISTRO_NAME;</filename> | ||
| 189 | branch: | ||
| 190 | <literallayout class='monospaced'> | ||
| 191 | $ cd ~/poky/poky-extras | ||
| 192 | $ git checkout -b &DISTRO_NAME; origin/&DISTRO_NAME; | ||
| 193 | Branch &DISTRO_NAME; set up to track remote branch &DISTRO_NAME; from origin. | ||
| 194 | Switched to a new branch '&DISTRO_NAME;' | ||
| 195 | </literallayout> | ||
| 196 | </para> | ||
| 197 | </section> | ||
| 198 | |||
| 199 | <section id='setting-up-the-bare-clone-and-its-copy'> | ||
| 200 | <title>Setting Up the Bare Clone and its Copy</title> | ||
| 201 | |||
| 202 | <para> | ||
| 203 | This example modifies the <filename>linux-yocto-3.4</filename> kernel. | ||
| 204 | Thus, you need to create a bare clone of that kernel and then make a copy of the | ||
| 205 | bare clone. | ||
| 206 | See the bulleted item | ||
| 207 | "<link linkend='local-kernel-files'>Yocto Project Kernel</link>" | ||
| 208 | for information on how to do that. | ||
| 209 | </para> | ||
| 210 | |||
| 211 | <para> | ||
| 212 | The bare clone exists for the kernel build tools and simply as the receiving end | ||
| 213 | of <filename>git push</filename> | ||
| 214 | commands after you make edits and commits inside the copy of the clone. | ||
| 215 | The copy (<filename>my-linux-yocto-3.4-work</filename> in this example) has to have | ||
| 216 | a local branch created and checked out for your work. | ||
| 217 | This example uses <filename>common-pc-base</filename> as the local branch. | ||
| 218 | The following commands create and checkout the branch: | ||
| 219 | <literallayout class='monospaced'> | ||
| 220 | $ cd ~/my-linux-yocto-3.4-work | ||
| 221 | $ git checkout -b standard-common-pc-base origin/standard/common-pc/base | ||
| 222 | Branch standard-common-pc-base set up to track remote branch | ||
| 223 | standard/common-pc/base from origin. | ||
| 224 | Switched to a new branch 'standard-common-pc-base' | ||
| 225 | </literallayout> | ||
| 226 | </para> | ||
| 227 | </section> | ||
| 228 | |||
| 229 | <section id='building-and-booting-the-default-qemu-kernel-image'> | ||
| 230 | <title>Building and Booting the Default QEMU Kernel Image</title> | ||
| 231 | |||
| 232 | <para> | ||
| 233 | Before we make changes to the kernel source files, this example first builds the | ||
| 234 | default image and then boots it inside the QEMU emulator. | ||
| 235 | <note> | ||
| 236 | Because a full build can take hours, you should check two variables in the | ||
| 237 | <filename>build</filename> directory that is created after you source the | ||
| 238 | <filename>&OE_INIT_FILE;</filename> script. | ||
| 239 | You can find these variables | ||
| 240 | <filename>BB_NUMBER_THREADS</filename> and <filename>PARALLEL_MAKE</filename> | ||
| 241 | in the <filename>build/conf</filename> directory in the | ||
| 242 | <filename>local.conf</filename> configuration file. | ||
| 243 | By default, these variables are commented out. | ||
| 244 | If your host development system supports multi-core and multi-thread capabilities, | ||
| 245 | you can uncomment these statements and set the variables to significantly shorten | ||
| 246 | the full build time. | ||
| 247 | As a guideline, set both <filename>BB_NUMBER_THREADS</filename> and | ||
| 248 | <filename>PARALLEL_MAKE</filename> to twice the number | ||
| 249 | of cores your machine supports. | ||
| 250 | </note> | ||
| 251 | The following two commands <filename>source</filename> the build environment setup script | ||
| 252 | and build the default <filename>qemux86</filename> image. | ||
| 253 | If necessary, the script creates the build directory: | ||
| 254 | <literallayout class='monospaced'> | ||
| 255 | $ cd ~/poky | ||
| 256 | $ source &OE_INIT_FILE; | ||
| 257 | You had no conf/local.conf file. This configuration file has therefore been | ||
| 258 | created for you with some default values. You may wish to edit it to use a | ||
| 259 | different MACHINE (target hardware) or enable parallel build options to take | ||
| 260 | advantage of multiple cores for example. See the file for more information as | ||
| 261 | common configuration options are commented. | ||
| 262 | |||
| 263 | The Yocto Project has extensive documentation about OE including a reference manual | ||
| 264 | which can be found at: | ||
| 265 | http://yoctoproject.org/documentation | ||
| 266 | |||
| 267 | For more information about OpenEmbedded see their website: | ||
| 268 | http://www.openembedded.org/ | ||
| 269 | |||
| 270 | You had no conf/bblayers.conf file. The configuration file has been created for | ||
| 271 | you with some default values. To add additional metadata layers into your | ||
| 272 | configuration please add entries to this file. | ||
| 273 | |||
| 274 | The Yocto Project has extensive documentation about OE including a reference manual | ||
| 275 | which can be found at: | ||
| 276 | http://yoctoproject.org/documentation | ||
| 277 | |||
| 278 | For more information about OpenEmbedded see their website: | ||
| 279 | http://www.openembedded.org/ | ||
| 280 | |||
| 281 | |||
| 282 | |||
| 283 | ### Shell environment set up for builds. ### | ||
| 284 | |||
| 285 | You can now run 'bitbake <target>>' | ||
| 286 | |||
| 287 | Common targets are: | ||
| 288 | core-image-minimal | ||
| 289 | core-image-sato | ||
| 290 | meta-toolchain | ||
| 291 | meta-toolchain-sdk | ||
| 292 | adt-installer | ||
| 293 | meta-ide-support | ||
| 294 | |||
| 295 | You can also run generated qemu images with a command like 'runqemu qemux86' | ||
| 296 | </literallayout> | ||
| 297 | </para> | ||
| 298 | |||
| 299 | <para> | ||
| 300 | The following <filename>bitbake</filename> command starts the build: | ||
| 301 | <literallayout class='monospaced'> | ||
| 302 | $ bitbake -k core-image-minimal | ||
| 303 | </literallayout> | ||
| 304 | <note>Be sure to check the settings in the <filename>local.conf</filename> | ||
| 305 | before starting the build.</note> | ||
| 306 | </para> | ||
| 307 | |||
| 308 | <para> | ||
| 309 | After the build completes, you can start the QEMU emulator using the resulting image | ||
| 310 | <filename>qemux86</filename> as follows: | ||
| 311 | <literallayout class='monospaced'> | ||
| 312 | $ runqemu qemux86 | ||
| 313 | </literallayout> | ||
| 314 | </para> | ||
| 315 | |||
| 316 | <para> | ||
| 317 | As the image boots in the emulator, console message and status output appears | ||
| 318 | across the terminal window. | ||
| 319 | Because the output scrolls by quickly, it is difficult to read. | ||
| 320 | To examine the output, you log into the system using the | ||
| 321 | login <filename>root</filename> with no password. | ||
| 322 | Once you are logged in, issue the following command to scroll through the | ||
| 323 | console output: | ||
| 324 | <literallayout class='monospaced'> | ||
| 325 | # dmesg | less | ||
| 326 | </literallayout> | ||
| 327 | </para> | ||
| 328 | |||
| 329 | <para> | ||
| 330 | Take note of the output as you will want to look for your inserted print command output | ||
| 331 | later in the example. | ||
| 332 | </para> | ||
| 333 | </section> | ||
| 334 | |||
| 335 | <section id='changing-the-source-code-and-pushing-it-to-the-bare-clone'> | ||
| 336 | <title>Changing the Source Code and Pushing it to the Bare Clone</title> | ||
| 337 | |||
| 338 | <para> | ||
| 339 | The file you change in this example is named <filename>calibrate.c</filename> | ||
| 340 | and is located in the <filename>my-linux-yocto-3.4-work</filename> Git repository | ||
| 341 | (the copy of the bare clone) in <filename>init</filename>. | ||
| 342 | This example simply inserts several <filename>printk</filename> statements | ||
| 343 | at the beginning of the <filename>calibrate_delay</filename> function. | ||
| 344 | </para> | ||
| 345 | |||
| 346 | <para> | ||
| 347 | Here is the unaltered code at the start of this function: | ||
| 348 | <literallayout class='monospaced'> | ||
| 349 | void __cpuinit calibrate_delay(void) | ||
| 350 | { | ||
| 351 | unsigned long lpj; | ||
| 352 | static bool printed; | ||
| 353 | int this_cpu = smp_processor_id(); | ||
| 354 | |||
| 355 | if (per_cpu(cpu_loops_per_jiffy, this_cpu)) { | ||
| 356 | . | ||
| 357 | . | ||
| 358 | . | ||
| 359 | </literallayout> | ||
| 360 | </para> | ||
| 361 | |||
| 362 | <para> | ||
| 363 | Here is the altered code showing five new <filename>printk</filename> statements | ||
| 364 | near the top of the function: | ||
| 365 | <literallayout class='monospaced'> | ||
| 366 | void __cpuinit calibrate_delay(void) | ||
| 367 | { | ||
| 368 | unsigned long lpj; | ||
| 369 | static bool printed; | ||
| 370 | int this_cpu = smp_processor_id(); | ||
| 371 | |||
| 372 | printk("*************************************\n"); | ||
| 373 | printk("* *\n"); | ||
| 374 | printk("* HELLO YOCTO KERNEL *\n"); | ||
| 375 | printk("* *\n"); | ||
| 376 | printk("*************************************\n"); | ||
| 377 | |||
| 378 | if (per_cpu(cpu_loops_per_jiffy, this_cpu)) { | ||
| 379 | . | ||
| 380 | . | ||
| 381 | . | ||
| 382 | </literallayout> | ||
| 383 | </para> | ||
| 384 | |||
| 385 | <para> | ||
| 386 | After making and saving your changes, you need to stage them for the push. | ||
| 387 | The following Git commands are one method of staging and committing your changes: | ||
| 388 | <literallayout class='monospaced'> | ||
| 389 | $ git add calibrate.c | ||
| 390 | $ git commit --signoff | ||
| 391 | </literallayout> | ||
| 392 | </para> | ||
| 393 | |||
| 394 | <para> | ||
| 395 | Once the source code has been modified, you need to use Git to push the changes to | ||
| 396 | the bare clone. | ||
| 397 | If you do not push the changes, then the OpenEmbedded build system will not pick | ||
| 398 | up the changed source files. | ||
| 399 | </para> | ||
| 400 | |||
| 401 | <para> | ||
| 402 | The following command pushes the changes to the bare clone: | ||
| 403 | <literallayout class='monospaced'> | ||
| 404 | $ git push origin standard-common-pc-base:standard/default/common-pc/base | ||
| 405 | </literallayout> | ||
| 406 | </para> | ||
| 407 | </section> | ||
| 408 | |||
| 409 | <section id='changing-build-parameters-for-your-build'> | ||
| 410 | <title>Changing Build Parameters for Your Build</title> | ||
| 411 | |||
| 412 | <para> | ||
| 413 | At this point, the source has been changed and pushed. | ||
| 414 | The example now defines some variables used by the OpenEmbedded build system | ||
| 415 | to locate your kernel source. | ||
| 416 | You essentially need to identify where to find the kernel recipe and the changed source code. | ||
| 417 | You also need to be sure some basic configurations are in place that identify the | ||
| 418 | type of machine you are building and to help speed up the build should your host support | ||
| 419 | multiple-core and thread capabilities. | ||
| 420 | </para> | ||
| 421 | |||
| 422 | <para> | ||
| 423 | Do the following to make sure the build parameters are set up for the example. | ||
| 424 | Once you set up these build parameters, they do not have to change unless you | ||
| 425 | change the target architecture of the machine you are building or you move | ||
| 426 | the bare clone, copy of the clone, or the <filename>poky-extras</filename> repository: | ||
| 427 | <itemizedlist> | ||
| 428 | <listitem><para><emphasis>Build for the Correct Target Architecture:</emphasis> The | ||
| 429 | <filename>local.conf</filename> file in the build directory defines the build's | ||
| 430 | target architecture. | ||
| 431 | By default, <filename>MACHINE</filename> is set to | ||
| 432 | <filename>qemux86</filename>, which specifies a 32-bit | ||
| 433 | <trademark class='registered'>Intel</trademark> Architecture | ||
| 434 | target machine suitable for the QEMU emulator. | ||
| 435 | In this example, <filename>MACHINE</filename> is correctly configured. | ||
| 436 | </para></listitem> | ||
| 437 | <listitem><para><emphasis>Optimize Build Time:</emphasis> Also in the | ||
| 438 | <filename>local.conf</filename> file are two variables that can speed your | ||
| 439 | build time if your host supports multi-core and multi-thread capabilities: | ||
| 440 | <filename>BB_NUMBER_THREADS</filename> and <filename>PARALLEL_MAKE</filename>. | ||
| 441 | If the host system has multiple cores then you can optimize build time | ||
| 442 | by setting both these variables to twice the number of | ||
| 443 | cores.</para></listitem> | ||
| 444 | <listitem><para><emphasis>Identify Your <filename>meta-kernel-dev</filename> | ||
| 445 | Layer:</emphasis> The <filename>BBLAYERS</filename> variable in the | ||
| 446 | <filename>bblayers.conf</filename> file found in the | ||
| 447 | <filename>poky/build/conf</filename> directory needs to have the path to your local | ||
| 448 | <filename>meta-kernel-dev</filename> layer. | ||
| 449 | By default, the <filename>BBLAYERS</filename> variable contains paths to | ||
| 450 | <filename>meta</filename> and <filename>meta-yocto</filename> in the | ||
| 451 | <filename>poky</filename> Git repository. | ||
| 452 | Add the path to your <filename>meta-kernel-dev</filename> location. | ||
| 453 | Be sure to substitute your user information in the statement. | ||
| 454 | Here is an example: | ||
| 455 | <literallayout class='monospaced'> | ||
| 456 | BBLAYERS = " \ | ||
| 457 | /home/scottrif/poky/meta \ | ||
| 458 | /home/scottrif/poky/meta-yocto \ | ||
| 459 | /home/scottrif/poky/meta-yocto-bsp \ | ||
| 460 | /home/scottrif/poky/poky-extras/meta-kernel-dev \ | ||
| 461 | " | ||
| 462 | </literallayout></para></listitem> | ||
| 463 | <listitem><para><emphasis>Identify Your Source Files:</emphasis> In the | ||
| 464 | <filename>linux-yocto_3.4.bbappend</filename> file located in the | ||
| 465 | <filename>poky-extras/meta-kernel-dev/recipes-kernel/linux</filename> | ||
| 466 | directory, you need to identify the location of the | ||
| 467 | local source code, which in this example is the bare clone named | ||
| 468 | <filename>linux-yocto-3.4.git</filename>. | ||
| 469 | To do this, set the <filename>KSRC_linux_yocto</filename> variable to point to your | ||
| 470 | local <filename>linux-yocto-3.4.git</filename> Git repository by adding the | ||
| 471 | following statement. | ||
| 472 | Also, be sure the <filename>SRC_URI</filename> variable is pointing to | ||
| 473 | your kernel source files by removing the comment. | ||
| 474 | Finally, be sure to substitute your user information in the statement: | ||
| 475 | <literallayout class='monospaced'> | ||
| 476 | KSRC_linux_yocto_3_4 ?= "/home/scottrif/linux-yocto-3.4.git" | ||
| 477 | SRC_URI = "git://${KSRC_linux_yocto_3_4};protocol=file;nocheckout=1;branch=${KBRANCH},meta;name=machine,meta" | ||
| 478 | </literallayout></para></listitem> | ||
| 479 | </itemizedlist> | ||
| 480 | </para> | ||
| 481 | |||
| 482 | <note> | ||
| 483 | <para>Before attempting to build the modified kernel, there is one more set of changes you | ||
| 484 | need to make in the <filename>meta-kernel-dev</filename> layer. | ||
| 485 | Because all the kernel <filename>.bbappend</filename> files are parsed during the | ||
| 486 | build process regardless of whether you are using them or not, you should either | ||
| 487 | comment out the <filename>COMPATIBLE_MACHINE</filename> statements in all | ||
| 488 | unused <filename>.bbappend</filename> files, or simply remove (or rename) all the files | ||
| 489 | except the one your are using for the build | ||
| 490 | (i.e. <filename>linux-yocto_3.4.bbappend</filename> in this example).</para> | ||
| 491 | <para>If you do not make one of these two adjustments, your machine will be compatible | ||
| 492 | with all the kernel recipes in the <filename>meta-kernel-dev</filename> layer. | ||
| 493 | When your machine is comapatible with all the kernel recipes, the build attempts | ||
| 494 | to build all kernels in the layer. | ||
| 495 | You could end up with build errors blocking your work.</para> | ||
| 496 | </note> | ||
| 497 | </section> | ||
| 498 | |||
| 499 | <section id='building-and-booting-the-modified-qemu-kernel-image'> | ||
| 500 | <title>Building and Booting the Modified QEMU Kernel Image</title> | ||
| 501 | |||
| 502 | <para> | ||
| 503 | Next, you need to build the modified image. | ||
| 504 | Do the following: | ||
| 505 | <orderedlist> | ||
| 506 | <listitem><para>Your environment should be set up since you previously sourced | ||
| 507 | the <filename>&OE_INIT_FILE;</filename> script. | ||
| 508 | If it isn't, source the script again from <filename>poky</filename>. | ||
| 509 | <literallayout class='monospaced'> | ||
| 510 | $ cd ~/poky | ||
| 511 | $ source &OE_INIT_FILE; | ||
| 512 | </literallayout> | ||
| 513 | </para></listitem> | ||
| 514 | <listitem><para>Be sure old images are cleaned out by running the | ||
| 515 | <filename>cleanall</filename> BitBake task as follows from your build directory: | ||
| 516 | <literallayout class='monospaced'> | ||
| 517 | $ bitbake -c cleanall linux-yocto | ||
| 518 | </literallayout></para> | ||
| 519 | <para><note>Never remove any files by hand from the <filename>tmp/deploy</filename> | ||
| 520 | directory insided the build directory. | ||
| 521 | Always use the BitBake <filename>cleanall</filename> task to clear | ||
| 522 | out previous builds.</note></para></listitem> | ||
| 523 | <listitem><para>Next, build the kernel image using this command: | ||
| 524 | <literallayout class='monospaced'> | ||
| 525 | $ bitbake -k core-image-minimal | ||
| 526 | </literallayout></para></listitem> | ||
| 527 | <listitem><para>Finally, boot the modified image in the QEMU emulator | ||
| 528 | using this command: | ||
| 529 | <literallayout class='monospaced'> | ||
| 530 | $ runqemu qemux86 | ||
| 531 | </literallayout></para></listitem> | ||
| 532 | </orderedlist> | ||
| 533 | </para> | ||
| 534 | |||
| 535 | <para> | ||
| 536 | Log into the machine using <filename>root</filename> with no password and then | ||
| 537 | use the following shell command to scroll through the console's boot output. | ||
| 538 | <literallayout class='monospaced'> | ||
| 539 | # dmesg | less | ||
| 540 | </literallayout> | ||
| 541 | </para> | ||
| 542 | |||
| 543 | <para> | ||
| 544 | You should see the results of your <filename>printk</filename> statements | ||
| 545 | as part of the output. | ||
| 546 | </para> | ||
| 547 | </section> | ||
| 548 | </section> | ||
| 549 | </appendix> | ||
| 550 | |||
| 551 | <!-- | ||
| 552 | vim: expandtab tw=80 ts=4 | ||
| 553 | --> | ||
diff --git a/documentation/dev-manual/dev-manual-model.xml b/documentation/dev-manual/dev-manual-model.xml index 844e0dc851..c96b2dda63 100644 --- a/documentation/dev-manual/dev-manual-model.xml +++ b/documentation/dev-manual/dev-manual-model.xml | |||
| @@ -13,9 +13,6 @@ | |||
| 13 | <listitem><para><emphasis>System Development:</emphasis> | 13 | <listitem><para><emphasis>System Development:</emphasis> |
| 14 | System Development covers Board Support Package (BSP) development and kernel | 14 | System Development covers Board Support Package (BSP) development and kernel |
| 15 | modification or configuration. | 15 | modification or configuration. |
| 16 | If you want to examine a specific example of the kernel modification and | ||
| 17 | configuration model, | ||
| 18 | see the "<link linkend='dev-manual-kernel-appendix'>Kernel Modification Example</link>" appendix. | ||
| 19 | For an example on how to create a BSP, see the | 16 | For an example on how to create a BSP, see the |
| 20 | "<ulink url='&YOCTO_DOCS_BSP_URL;#creating-a-new-bsp-layer-using-the-yocto-bsp-script'>Creating a New BSP Layer Using the yocto-bsp Script</ulink>" | 17 | "<ulink url='&YOCTO_DOCS_BSP_URL;#creating-a-new-bsp-layer-using-the-yocto-bsp-script'>Creating a New BSP Layer Using the yocto-bsp Script</ulink>" |
| 21 | section in the Yocto Project Board Support Package (BSP) Developer's Guide. | 18 | section in the Yocto Project Board Support Package (BSP) Developer's Guide. |
| @@ -234,9 +231,11 @@ | |||
| 234 | kernel architecture and the steps to modify the kernel. | 231 | kernel architecture and the steps to modify the kernel. |
| 235 | For a complete discussion of the kernel, see the | 232 | For a complete discussion of the kernel, see the |
| 236 | <ulink url='&YOCTO_DOCS_KERNEL_URL;'>Yocto Project Kernel Architecture and Use Manual</ulink>. | 233 | <ulink url='&YOCTO_DOCS_KERNEL_URL;'>Yocto Project Kernel Architecture and Use Manual</ulink>. |
| 237 | You can reference the appendix | 234 | You can reference the |
| 238 | "<link linkend='dev-manual-kernel-appendix'>Kernel Modification Example</link>" | 235 | "<link linkend='patching-the-kernel'>Patching the Kernel</link>" section |
| 239 | for a detailed example that changes the configuration of a kernel. | 236 | for an example that changes the source code of the kernel. |
| 237 | For information on how to configure the kernel, see the | ||
| 238 | "<link linkend='configuring-the-kernel'>Configuring the Kernel</link> section. | ||
| 240 | </para> | 239 | </para> |
| 241 | 240 | ||
| 242 | <section id='kernel-overview'> | 241 | <section id='kernel-overview'> |
| @@ -364,8 +363,8 @@ | |||
| 364 | you work. | 363 | you work. |
| 365 | Once you make corrections, you must use Git to push the committed changes to the | 364 | Once you make corrections, you must use Git to push the committed changes to the |
| 366 | bare clone. | 365 | bare clone. |
| 367 | The example in <xref linkend='modifying-the-kernel-source-code'> | 366 | <!-- The example in <xref linkend='modifying-the-kernel-source-code'> |
| 368 | Modifying the Kernel Source Code</xref> provides a detailed example. | 367 | Modifying the Kernel Source Code</xref> provides a detailed example. --> |
| 369 | </para> | 368 | </para> |
| 370 | 369 | ||
| 371 | <para> | 370 | <para> |
| @@ -394,7 +393,7 @@ | |||
| 394 | branching strategy, see the | 393 | branching strategy, see the |
| 395 | <ulink url='&YOCTO_DOCS_KERNEL_URL;'>Yocto Project Kernel Architecture and Use Manual</ulink>. | 394 | <ulink url='&YOCTO_DOCS_KERNEL_URL;'>Yocto Project Kernel Architecture and Use Manual</ulink>. |
| 396 | You can also reference the | 395 | You can also reference the |
| 397 | "<link linkend='modifying-the-kernel-source-code'>Modifying the Kernel Source Code</link>" | 396 | "<link linkend='patching-the-kernel'>Patching the Kernel</link>" |
| 398 | section for a detailed example that modifies the kernel. | 397 | section for a detailed example that modifies the kernel. |
| 399 | </para> | 398 | </para> |
| 400 | </section> | 399 | </section> |
| @@ -602,8 +601,8 @@ | |||
| 602 | If your target architecture is similar to a supported architecture, you can | 601 | If your target architecture is similar to a supported architecture, you can |
| 603 | modify the kernel image before you build it. | 602 | modify the kernel image before you build it. |
| 604 | See the | 603 | See the |
| 605 | "<link linkend='dev-manual-kernel-appendix'>Kernel Modification Example</link>" | 604 | "<link linkend='patching-the-kernel'>Patching the Kernel</link>" |
| 606 | appendix later in this manual for an example.</para></listitem> | 605 | section for an example.</para></listitem> |
| 607 | </itemizedlist></para> | 606 | </itemizedlist></para> |
| 608 | <para>For information on pre-built kernel image naming schemes for images | 607 | <para>For information on pre-built kernel image naming schemes for images |
| 609 | that can run on the QEMU emulator, see the | 608 | that can run on the QEMU emulator, see the |
diff --git a/documentation/dev-manual/dev-manual.xml b/documentation/dev-manual/dev-manual.xml index a5856e0995..eff0dce1f0 100644 --- a/documentation/dev-manual/dev-manual.xml +++ b/documentation/dev-manual/dev-manual.xml | |||
| @@ -80,8 +80,6 @@ | |||
| 80 | 80 | ||
| 81 | <xi:include href="dev-manual-model.xml"/> | 81 | <xi:include href="dev-manual-model.xml"/> |
| 82 | 82 | ||
| 83 | <xi:include href="dev-manual-kernel-appendix.xml"/> | ||
| 84 | |||
| 85 | </book> | 83 | </book> |
| 86 | <!-- | 84 | <!-- |
| 87 | vim: expandtab tw=80 ts=4 | 85 | vim: expandtab tw=80 ts=4 |
