Poky-Tiny

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Poky-tiny is a variant of the poky distribution which is stripped down to minimal configuration.

It is intended to be useful for a few different purposes:

  • as a demonstration of techniques useful for reducing other images
  • as a springboard for very low-end distributions and images
  • as a place to experiment with whole-system optimization techniques

It was written by Darren Hart, and is available by setting your DISTRO in conf/local.conf to DISTRO=poky-tiny.

This page is a work in progress - the following sections would be good to fill out:

FAQ

  • where is poky-tiny defined?
    • poky-tiny is defined in <yocto-dir>/meta-yocto/conf/distro/poky-tiny.conf. Some other recipes and images have been modified to support the features in poky-tiny.
  • What images are supported?
  • What machines (are there any restrictions)?
  • What features have been eliminated?
  • What is the size difference between poky-tiny and poky (core-image-minimal)?
  • Are there differences in the way poky-tiny is customized, from the way default 'poky' is customized?
    • eg. gotchas for adding to IMAGE_

Creating your own tiny-based distro

You can create your own distro, based on the tiny work, by copying the poky-tiny.conf file to your own layer, and editing it from there.

Assuming you are calling your layer 'meta-foo', you could do the following:

  • create your meta-foo layer (see other docs for this)
  • copy the poky-tiny distro configuration file to your own layer
$ install -p meta-foo/conf/distro
$ cp meta-yocto/conf/distro/poky-tiny.conf meta-foo/conf/distro/foo-tiny.conf
  • edit your conf/local.conf to use your foo-tiny.conf distro
$ vi <build-dir>/conf/local.conf
[change it so "DISTRO?=foo-tiny"]

Adjusting poky-tiny

Controlling LIBC features

Inside foo-tiny.conf (derived from poky-tiny.conf), you can specify what LIBC features to support by modifying the DISTRO_FEATURES_LIBC variable.

This variable is declared to be a space-separated list of other DISTRO_FEATURES_LIBC_xxx variables. To turn on or off features in libc, edit the values of these variables.

eglibc

To see different options that are available, see the file: <yocto-dir>/meta/recipes-core/eglibc/eglibc-options.inc

Listed in that file are the routines: distro_features_check_deps() and features_to_eglibc_settings(), which map items listed in DISTRO_FEATURES_LIBC into specific eglibc settings.

uclibc

To see different options that are available, see the file: <yocto-dir>/meta/recipes-core/uclibc/uclibc-config.inc

Listed in that file are the routines: features_to_uclibc_settings(), which map items listed in DISTRO_FEATURES_LIBC into specific uclibc settings.

Controlling kernel features

Controlling busybox features

Troubleshooting the build

Invoking qemu with poky-tiny images

Runqemu doesn't understand poky-tiny (or initramfs?). Try executing qemu directly instead:

$ qemu-system-i386 -kernel path/to/kernel -initrd path/to/image.cpio.gz -nographic -append "console=ttyS0 root=/dev/ram0"

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