Richard Purdie 02bc1b422b bitbake: hashserv: Improve behaviour for better determinism/sstate reuse
We have a choice of policy with hashequivalence - whether to reduce
sstate duplication in the sstate feed to a minimum or have maximal
sstate reuse from the user's perspective.

The challenge is that non-matching outhashes are generated due to
determinism issues, or due to differences in host gcc version,
architecture and so on and the question is how to reconcile then.

The approach before this patch is that any new match is added and
matches can update. This has the side effect that a queried value
from the server can change due to the replacement and you may not
always get the same value from the server. With the client side
caching bitbake has, this can be suboptimal and when using the
autobuilder sstate feed, it results in poor artefact reuse.

This patch switches to the other possible behaviour, once a hash is
assigned, it doesn't change. This means some sstate artefacts may be
duplicated but dependency chains aren't invalidated which I suspect
may give better overall performance.

Update the tests to match the new behaviour.

(Bitbake rev: 20d6ac753efa364349100cdc863e5eabec8e5b78)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
2021-10-11 11:00:06 +01:00
2021-07-19 18:07:21 +01:00

Poky

Poky is an integration of various components to form a pre-packaged build system and development environment which is used as a development and validation tool by the Yocto Project. It features support for building customised embedded style device images and custom containers. There are reference demo images ranging from X11/GTK+ to Weston, commandline and more. The system supports cross-architecture application development using QEMU emulation and a standalone toolchain and SDK suitable for IDE integration.

Additional information on the specifics of hardware that Poky supports is available in README.hardware. Further hardware support can easily be added in the form of BSP layers which extend the systems capabilities in a modular way. Many layers are available and can be found through the layer index.

As an integration layer Poky consists of several upstream projects such as BitBake, OpenEmbedded-Core, Yocto documentation, the 'meta-yocto' layer which has configuration and hardware support components. These components are all part of the Yocto Project and OpenEmbedded ecosystems.

The Yocto Project has extensive documentation about the system including a reference manual which can be found at https://docs.yoctoproject.org/

OpenEmbedded is the build architecture used by Poky and the Yocto project. For information about OpenEmbedded, see the OpenEmbedded website.

Contribution Guidelines

The project works using a mailing list patch submission process. Patches should be sent to the mailing list for the repository the components originate from (see below). Throughout the Yocto Project, the README files in the component in question should detail where to send patches, who the maintainers are and where bugs should be reported.

A guide to submitting patches to OpenEmbedded is available at:

https://www.openembedded.org/wiki/How_to_submit_a_patch_to_OpenEmbedded

There is good documentation on how to write/format patches at:

https://www.openembedded.org/wiki/Commit_Patch_Message_Guidelines

Where to Send Patches

As Poky is an integration repository (built using a tool called combo-layer), patches against the various components should be sent to their respective upstreams:

OpenEmbedded-Core (files in meta/, meta-selftest/, meta-skeleton/, scripts/):

BitBake (files in bitbake/):

Documentation (files in documentation/):

meta-yocto (files in meta-poky/, meta-yocto-bsp/):

If in doubt, check the openembedded-core git repository for the content you intend to modify as most files are from there unless clearly one of the above categories. Before sending, be sure the patches apply cleanly to the current git repository branch in question.

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