From c527fd1f14c27855a37f2e8ac5346ce8d940ced2 Mon Sep 17 00:00:00 2001 From: Tudor Florea Date: Thu, 16 Oct 2014 03:05:19 +0200 Subject: initial commit for Enea Linux 4.0-140929 Migrated from the internal git server on the daisy-enea-point-release branch Signed-off-by: Tudor Florea --- documentation/ref-manual/ref-features.xml | 344 ++++++++++++++++++++++++++++++ 1 file changed, 344 insertions(+) create mode 100644 documentation/ref-manual/ref-features.xml (limited to 'documentation/ref-manual/ref-features.xml') diff --git a/documentation/ref-manual/ref-features.xml b/documentation/ref-manual/ref-features.xml new file mode 100644 index 0000000000..f351931ab6 --- /dev/null +++ b/documentation/ref-manual/ref-features.xml @@ -0,0 +1,344 @@ + %poky; ] > + + + Features + + + This chapter provides a reference of shipped machine and distro features + you can include as part of the image, a reference on image types you can + build, and a reference on feature backfilling. + + + + Features provide a mechanism for working out which packages + should be included in the generated images. + Distributions can select which features they want to support through the + DISTRO_FEATURES + variable, which is set in the poky.conf distribution configuration file. + Machine features are set in the + MACHINE_FEATURES + variable, which is set in the machine configuration file and + specifies the hardware features for a given machine. + + + + These two variables combine to work out which kernel modules, + utilities, and other packages to include. + A given distribution can support a selected subset of features so some machine features might not + be included if the distribution itself does not support them. + + + + One method you can use to determine which recipes are checking to see if a + particular feature is contained or not is to grep through + the Metadata + for the feature. + Here is an example that discovers the recipes whose build is potentially + changed based on a given feature: + + $ cd poky + $ git grep 'contains.*MACHINE_FEATURES.*<feature>' + + + +
+ Machine Features + + + The items below are features you can use with + MACHINE_FEATURES. + Features do not have a one-to-one correspondence to packages, and they can + go beyond simply controlling the installation of a package or packages. + Sometimes a feature can influence how certain recipes are built. + For example, a feature might determine whether a particular configure option + is specified within do_configure for a particular + recipe. + + + + This feature list only represents features as shipped with the Yocto Project metadata: + + acpi: Hardware has ACPI (x86/x86_64 only) + + alsa: Hardware has ALSA audio drivers + + apm: Hardware uses APM (or APM emulation) + + bluetooth: Hardware has integrated BT + + ext2: Hardware HDD or Microdrive + + irda: Hardware has IrDA support + + keyboard: Hardware has a keyboard + + pci: Hardware has a PCI bus + + pcmcia: Hardware has PCMCIA or CompactFlash sockets + + screen: Hardware has a screen + + serial: Hardware has serial support (usually RS232) + + touchscreen: Hardware has a touchscreen + + usbgadget: Hardware is USB gadget device capable + + usbhost: Hardware is USB Host capable + + wifi: Hardware has integrated WiFi + + + +
+ +
+ Distro Features + + + The items below are features you can use with + DISTRO_FEATURES + to enable features across your distribution. + Features do not have a one-to-one correspondence to packages, + and they can go beyond simply controlling the installation of a + package or packages. + In most cases, the presence or absence of a feature translates to + the appropriate option supplied to the configure script during + do_configure for the recipes that optionally + support the feature. + + + + Some distro features are also machine features. + These select features make sense to be controlled both at + the machine and distribution configuration level. + See the + COMBINED_FEATURES + variable for more information. + + + + This list only represents features as shipped with the Yocto Project metadata: + + alsa: Include ALSA support + (OSS compatibility kernel modules installed if available). + + bluetooth: Include + bluetooth support (integrated BT only). + cramfs: Include CramFS + support. + directfb: + Include DirectFB support. + + ext2: Include tools for + supporting for devices with internal HDD/Microdrive for + storing files (instead of Flash only devices). + + ipsec: Include IPSec + support. + ipv6: Include IPv6 support. + + irda: Include IrDA support. + + keyboard: Include keyboard + support (e.g. keymaps will be loaded during boot). + + nfs: Include NFS client + support (for mounting NFS exports on device). + + opengl: + Include the Open Graphics Library, which is a + cross-language, multi-platform application programming + interface used for rendering two and three-dimensional + graphics. + pci: Include PCI bus + support. + pcmcia: Include + PCMCIA/CompactFlash support. + ppp: Include PPP dialup + support. + smbfs: Include SMB networks + client support (for mounting Samba/Microsoft Windows shares + on device). + systemd: Include support + for this init manager, which is a full + replacement of for init with parallel + starting of services, reduced shell overhead, and other + features. + This init manager is used by many + distributions. + usbgadget: Include USB + Gadget Device support (for USB networking/serial/storage). + + usbhost: Include USB Host + support (allows to connect external keyboard, mouse, + storage, network etc). + wayland: Include the + Wayland display server protocol and the library that + supports it. + wifi: Include WiFi support + (integrated only). + x11: Include the X server + and libraries. + + +
+ +
+ Image Features + + + The contents of images generated by the OpenEmbedded build system can be controlled by the + IMAGE_FEATURES + and EXTRA_IMAGE_FEATURES + variables that you typically configure in your image recipes. + Through these variables, you can add several different + predefined packages such as development utilities or packages with debug + information needed to investigate application problems or profile applications. + + + + Current list of + IMAGE_FEATURES contains the following: + + dbg-pkgs: Installs debug symbol packages for all packages + installed in a given image. + dev-pkgs: Installs development packages (headers and + extra library links) for all packages installed in a given image. + doc-pkgs: Installs documentation packages for all packages + installed in a given image. + nfs-server: Installs an NFS server. + read-only-rootfs: Creates + an image whose root filesystem is read-only. + See the + "Creating a Read-Only Root Filesystem" + section in the Yocto Project Development Manual for more + information. + splash: Enables showing a splash screen during boot. + By default, this screen is provided by psplash, which does + allow customization. + If you prefer to use an alternative splash screen package, you can do so by + setting the SPLASH variable + to a different package name (or names) within the image recipe or at the distro + configuration level. + ssh-server-dropbear: Installs the Dropbear minimal + SSH server. + + ssh-server-openssh: Installs the OpenSSH SSH server, + which is more full-featured than Dropbear. + Note that if both the OpenSSH SSH server and the Dropbear minimal SSH server + are present in IMAGE_FEATURES, then OpenSSH will take + precedence and Dropbear will not be installed. + staticdev-pkgs: Installs static development + packages (i.e. static libraries containing *.a files) for all + packages installed in a given image. + tools-debug: Installs debugging tools such as + strace and gdb. + For information on GDB, see the + "Debugging With the GNU Project Debugger (GDB) Remotely" + section in the Yocto Project Development Manual. + For information on tracing and profiling, see the + Yocto Project Profiling and Tracing Manual. + + tools-profile: Installs profiling tools such as + oprofile, exmap, and + LTTng. + For general information on user-space tools, see the + "User-Space Tools" + section in the Yocto Project Application Developer's Guide. + tools-sdk: Installs a full SDK that runs on the device. + + tools-testapps: Installs device testing tools (e.g. + touchscreen debugging). + x11: Installs the X server + x11-base: Installs the X server with a + minimal environment. + x11-sato: Installs the OpenedHand Sato environment. + + + +
+ +
+ Feature Backfilling + + + Sometimes it is necessary in the OpenEmbedded build system to extend + MACHINE_FEATURES + or DISTRO_FEATURES + to control functionality that was previously enabled and not able + to be disabled. + For these cases, we need to add an + additional feature item to appear in one of these variables, + but we do not want to force developers who have existing values + of the variables in their configuration to add the new feature + in order to retain the same overall level of functionality. + Thus, the OpenEmbedded build system has a mechanism to + automatically "backfill" these added features into existing + distro or machine configurations. + You can see the list of features for which this is done by + finding the + DISTRO_FEATURES_BACKFILL + and MACHINE_FEATURES_BACKFILL + variables in the meta/conf/bitbake.conf file. + + + + Because such features are backfilled by default into all + configurations as described in the previous paragraph, developers + who wish to disable the new features need to be able to selectively + prevent the backfilling from occurring. + They can do this by adding the undesired feature or features to the + DISTRO_FEATURES_BACKFILL_CONSIDERED + or MACHINE_FEATURES_BACKFILL_CONSIDERED + variables for distro features and machine features respectively. + + + + Here are two examples to help illustrate feature backfilling: + + The "pulseaudio" distro feature option: + Previously, PulseAudio support was enabled within the Qt and + GStreamer frameworks. + Because of this, the feature is backfilled and thus + enabled for all distros through the + DISTRO_FEATURES_BACKFILL + variable in the meta/conf/bitbake.conf file. + However, your distro needs to disable the feature. + You can disable the feature without affecting + other existing distro configurations that need PulseAudio support + by adding "pulseaudio" to + DISTRO_FEATURES_BACKFILL_CONSIDERED + in your distro's .conf file. + Adding the feature to this variable when it also + exists in the DISTRO_FEATURES_BACKFILL + variable prevents the build system from adding the feature to + your configuration's DISTRO_FEATURES, effectively disabling + the feature for that particular distro. + The "rtc" machine feature option: + Previously, real time clock (RTC) support was enabled for all + target devices. + Because of this, the feature is backfilled and thus enabled + for all machines through the MACHINE_FEATURES_BACKFILL + variable in the meta/conf/bitbake.conf file. + However, your target device does not have this capability. + You can disable RTC support for your device without + affecting other machines that need RTC support + by adding the feature to your machine's + MACHINE_FEATURES_BACKFILL_CONSIDERED + list in the machine's .conf file. + Adding the feature to this variable when it also + exists in the MACHINE_FEATURES_BACKFILL + variable prevents the build system from adding the feature to + your configuration's MACHINE_FEATURES, effectively + disabling RTC support for that particular machine. + + +
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