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authorScott Rifenbark <scott.m.rifenbark@intel.com>2012-10-08 08:49:23 -0700
committerRichard Purdie <richard.purdie@linuxfoundation.org>2012-10-10 15:18:11 +0100
commit274095d4c21a8f617a41f85a364db78e96f7bf4d (patch)
tree67f70f1dac528400a8dcfc89447c21235ff5475d /documentation/dev-manual/dev-manual-common-tasks.xml
parentd38325cbcad40d2fa0c60e2a7f2afd72bd97a455 (diff)
downloadpoky-274095d4c21a8f617a41f85a364db78e96f7bf4d.tar.gz
documentation: dev-manual - Updates to configuring Kernel section
Eliminated the section A.2, which had an example of how to use menuconfig in the kerenl example appendix. The information is now merged into the similar section in Chapter 4 "Common Tasks." It was decided that the Appendix A examples in the manual were too detailed for a general development guide. (From yocto-docs rev: f88ec421b257657f02cc0f132ec2580c17f07cef) Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Diffstat (limited to 'documentation/dev-manual/dev-manual-common-tasks.xml')
-rw-r--r--documentation/dev-manual/dev-manual-common-tasks.xml88
1 files changed, 81 insertions, 7 deletions
diff --git a/documentation/dev-manual/dev-manual-common-tasks.xml b/documentation/dev-manual/dev-manual-common-tasks.xml
index 824aac1236..918d884681 100644
--- a/documentation/dev-manual/dev-manual-common-tasks.xml
+++ b/documentation/dev-manual/dev-manual-common-tasks.xml
@@ -1352,6 +1352,8 @@
1352 <para> 1352 <para>
1353 The easiest way to define kernel configurations is to set them through the 1353 The easiest way to define kernel configurations is to set them through the
1354 <filename>menuconfig</filename> tool. 1354 <filename>menuconfig</filename> tool.
1355 This tool provides an interactive method with which
1356 to set kernel configurations.
1355 For general information on <filename>menuconfig</filename>, see 1357 For general information on <filename>menuconfig</filename>, see
1356 <ulink url='http://en.wikipedia.org/wiki/Menuconfig'></ulink>. 1358 <ulink url='http://en.wikipedia.org/wiki/Menuconfig'></ulink>.
1357 </para> 1359 </para>
@@ -1359,6 +1361,9 @@
1359 <para> 1361 <para>
1360 To use the <filename>menuconfig</filename> tool in the Yocto Project development 1362 To use the <filename>menuconfig</filename> tool in the Yocto Project development
1361 environment, you must build the tool using BitBake. 1363 environment, you must build the tool using BitBake.
1364 Thus, the environment must be set up using the <filename>&OE_INIT_FILE;</filename>
1365 script found in the
1366 <link linkend='build-directory'>Build Directory</link>.
1362 The following commands build and invoke <filename>menuconfig</filename> assuming the 1367 The following commands build and invoke <filename>menuconfig</filename> assuming the
1363 source directory top-level folder is <filename>~/poky</filename>: 1368 source directory top-level folder is <filename>~/poky</filename>:
1364 <literallayout class='monospaced'> 1369 <literallayout class='monospaced'>
@@ -1367,17 +1372,86 @@
1367 $ bitbake linux-yocto -c menuconfig 1372 $ bitbake linux-yocto -c menuconfig
1368 </literallayout> 1373 </literallayout>
1369 Once <filename>menuconfig</filename> comes up, its standard interface allows you to 1374 Once <filename>menuconfig</filename> comes up, its standard interface allows you to
1370 examine and configure all the kernel configuration parameters. 1375 interactively examine and configure all the kernel configuration parameters.
1371 Once you have made your changes, simply exit the tool and save your changes to 1376 After making your changes, simply exit the tool and save your changes to
1372 create an updated version of the <filename>.config</filename> configuration file. 1377 create an updated version of the <filename>.config</filename> configuration file.
1373 </para> 1378 </para>
1374 1379
1375 <para> 1380 <para>
1376 For an example that shows how to change a specific kernel option 1381 Consider an example that configures the <filename>linux-yocto-3.4</filename>
1377 using <filename>menuconfig</filename>, see the 1382 kernel.
1378 "<link linkend='changing-the-config-smp-configuration-using-menuconfig'>Changing 1383 The OpenEmbedded build system recognizes this kernel as
1379 the <filename>CONFIG_SMP</filename> Configuration Using <filename>menuconfig</filename></link>" 1384 <filename>linux-yocto</filename>.
1380 section. 1385 Thus, the following commands from the shell in which you previously sourced the
1386 environment initialization script cleans the shared state cache and the
1387 <ulink url='&YOCTO_DOCS_REF_URL;#var-WORKDIR'><filename>WORKDIR</filename></ulink>
1388 directory and then builds and launches <filename>menuconfig</filename>:
1389 <literallayout class='monospaced'>
1390 $ bitbake linux-yocto -c menuconfig
1391 </literallayout>
1392 </para>
1393
1394 <para>
1395 Once <filename>menuconfig</filename> launches, you use the interface
1396 to navigate through the selections to find the configuration settings in
1397 which you are interested.
1398 For example, consider the <filename>CONFIG_SMP</filename> configuration setting.
1399 You can find it at <filename>Processor Type and Features</filename> under
1400 the configuration selection <filename>Symmetric Multi-processing Support</filename>.
1401 After highlighting the selection, you can use the arrow keys to select or deselect
1402 the setting.
1403 When you are finished with all your selections, exit out and save them.
1404 </para>
1405
1406 <para>
1407 Saving the selections updates the <filename>.config</filename> configuration file.
1408 This is the file that the OpenEmbedded build system uses to configure the
1409 kernel during the build.
1410 You can find and examine this file in the build directory in
1411 <filename>tmp/work/</filename>.
1412 The actual <filename>.config</filename> is located in the area where the
1413 specific kernel is built.
1414 For example, if you were building a Linux Yocto kernel based on the
1415 Linux 3.4 kernel and you were building a QEMU image targeted for
1416 <filename>x86</filename> architecture, the
1417 <filename>.config</filename> file would be located here:
1418 <literallayout class='monospaced'>
1419 ~/poky/build/tmp/work/qemux86-poky-linux/linux-yocto-3.4.11+git1+84f...
1420 ...656ed30-r1/linux-qemux86-standard-build
1421 </literallayout>
1422 <note>
1423 The previous example directory is artificially split and many of the characters
1424 in the actual filename are omitted in order to make it more readable.
1425 Also, depending on the kernel you are using, the exact pathname
1426 for <filename>linux-yocto-3.4...</filename> might differ.
1427 </note>
1428 </para>
1429
1430 <para>
1431 Within the <filename>.config</filename> file, you can see the kernel settings.
1432 For example, the following entry shows that symmetric multi-processor support
1433 is not set:
1434 <literallayout class='monospaced'>
1435 # CONFIG_SMP is not set
1436 </literallayout>
1437 </para>
1438
1439 <para>
1440 A good method to isolate changed configurations is to use a combination of the
1441 <filename>menuconfig</filename> tool and simple shell commands.
1442 Before changing configurations with <filename>menuconfig</filename>, copy the
1443 existing <filename>.config</filename> and rename it to something else,
1444 use <filename>menuconfig</filename> to make
1445 as many changes an you want and save them, then compare the renamed configuration
1446 file against the newly created file.
1447 You can use the resulting differences as your base to create configuration fragments
1448 to permanently save in your kernel layer.
1449 <note>
1450 Be sure to make a copy of the <filename>.config</filename> and don't just
1451 rename it.
1452 The build system needs an existing <filename>.config</filename>
1453 from which to work.
1454 </note>
1381 </para> 1455 </para>
1382 </section> 1456 </section>
1383 1457