41 Locking and Unlocking Recipes Using `bblock`

By design, the OpenEmbedded build system builds everything from scratch unless BitBake determines that specific tasks do not require rebuilding. At startup, it computes a signature for all tasks, based on the task’s input. Then, it compares these signatures with the ones from the sstate cache (if they exist). Any changes cause the task to rerun.

During development, changes might trigger BitBake to rebuild certain recipes, even when we know they do not require rebuilding at that stage. For example, modifying a recipe can lead to rebuilding its native counterpart, which might prove unnecessary. Editing the python3 recipe, for instance, can prompt BitBake to rebuild python3-native along with any recipes that depend on it.

To prevent this, use bblock to lock specific tasks or recipes to specific signatures, forcing BitBake to use the sstate cache for them.

Attention

Use bblock only during the development phase.

Forcing BitBake to use the sstate cache, regardless of input changes, means the recipe metadata no longer directly reflect the output. Use this feature with caution. If you do not understand why signatures change, see the section on understanding what changed.

41.1 Locking tasks and recipes

To lock a recipe, use:

$ bblock recipe

You can also use a space-separated list of recipes to lock multiple recipes:

$ bblock recipe1 recipe2

Locking a recipe means locking all tasks of the recipe. If you need to lock only particular tasks, use the -t option with a comma-separated list of tasks:

$ bblock -t task1,task2 recipe

41.2 Unlocking tasks and recipes

To unlock a recipe, use the -r option:

$ bblock -r recipe

You can also use a space-separated list of recipes to unlock multiple recipes:

$ bblock -r recipe1 recipe2

Unlocking a recipe means unlocking all tasks of the recipe. If you need to unlock only particular tasks use the -t option with a comma-separated list of tasks:

$ bblock -r -t task1,task2 recipe

To unlock all recipes, do not specify any recipe:

$ bblock -r

41.3 Configuration file

bblock will dump the signatures in the build/conf/bblock.conf file, included by default in meta/conf/bitbake.conf.

To dump the file, use the -d option:

$ bblock -d

41.4 Locking mechanism

bblock computes the signature(s) of the task(s) and sets the 3 following variables: SIGGEN_LOCKEDSIGS, SIGGEN_LOCKEDSIGS_TYPES and SIGGEN_LOCKEDSIGS_TASKSIG_CHECK.

In particular, bblock sets:

SIGGEN_LOCKEDSIGS_TASKSIG_CHECK = "info"
SIGGEN_LOCKEDSIGS_TYPES += "${PACKAGE_ARCHS}"

SIGGEN_LOCKEDSIGS_<package_arch> += "<recipe>:<task>:<signature>"

This produces architecture specific locks and reminds user that some tasks have locked signatures.

41.5 Example

When working on the python3 recipe, we can lock python3-native with the following:

$ bblock python3-native
$ bblock -d
# Generated by bblock
SIGGEN_LOCKEDSIGS_TASKSIG_CHECK = "info"
SIGGEN_LOCKEDSIGS_TYPES += "${PACKAGE_ARCHS}"

SIGGEN_LOCKEDSIGS_x86_64 += "python3-native:do_patch:865859c27e603ba42025b7bb766c3cd4c0f477e4962cfd39128c0619d695fce7"
SIGGEN_LOCKEDSIGS_x86_64 += "python3-native:do_populate_sysroot:f8fa5d3194cef638416000252b959e86d0a19f6b7898e1f56b643c588cdd8605"
SIGGEN_LOCKEDSIGS_x86_64 += "python3-native:do_prepare_recipe_sysroot:fe295ac505d9d1143313424b201c6f3f2a0a90da40a13a905b86b874705f226a"
SIGGEN_LOCKEDSIGS_x86_64 += "python3-native:do_fetch:1b6e4728fee631bc7a8a7006855c5b8182a8224579e32e3d0a2db77c26459f25"
SIGGEN_LOCKEDSIGS_x86_64 += "python3-native:do_unpack:2ad74d6f865ef75c35c0e6bbe3f9a90923a6b2c62c18a3ddef514ea31fbc588f"
SIGGEN_LOCKEDSIGS_x86_64 += "python3-native:do_deploy_source_date_epoch:15f89b8483c1ad7507480f337619bb98c26e231227785eb3543db163593e7b42"
SIGGEN_LOCKEDSIGS_x86_64 += "python3-native:do_configure:7960c13d23270fdb12b3a7c426ce1da0d2f5c7cf5e5d3f5bdce5fa330eb7d482"
SIGGEN_LOCKEDSIGS_x86_64 += "python3-native:do_compile:012e1d4a63f1a78fc2143bd90d704dbcf5865c5257d6272aa7540ec1cd3063d9"
SIGGEN_LOCKEDSIGS_x86_64 += "python3-native:do_install:d3401cc2afa4c996beb154beaad3e45fa0272b9c56fb86e9db14ec3544c68f9d"
SIGGEN_LOCKEDSIGS_x86_64 += "python3-native:do_build:fa88bb7afb9046c0417c24a3fa98a058653805a8b00eda2c2d7fea68fc42f882"
SIGGEN_LOCKEDSIGS_x86_64 += "python3-native:do_collect_spdx_deps:cc9c53ba7c495567e9a38ec4801830c425c0d1f895aa2fc66930a2edd510d9b4"
SIGGEN_LOCKEDSIGS_x86_64 += "python3-native:do_create_spdx:766a1d09368438b7b5a1a8e2a8f823b2b731db44b57e67d8b3196de91966f9c5"
SIGGEN_LOCKEDSIGS_x86_64 += "python3-native:do_create_package_spdx:46f80faeab25575e9977ba3bf14c819489c3d489432ae5145255635108c21020"
SIGGEN_LOCKEDSIGS_x86_64 += "python3-native:do_recipe_qa:cb960cdb074e7944e894958db58f3dc2a0436ecf87c247feb3e095e214fec0e4"
SIGGEN_LOCKEDSIGS_x86_64 += "python3-native:do_populate_lic:15657441621ee83f15c2e650e7edbb036870b56f55e72e046c6142da3c5783fd"
SIGGEN_LOCKEDSIGS_x86_64 += "python3-native:do_create_manifest:24f0abbec221d27bbb2909b6e846288b12cab419f1faf9f5006ed80423d37e28"
SIGGEN_LOCKEDSIGS_x86_64 += "python3-native:do_addto_recipe_sysroot:bcb6a1905f113128de3f88d702b706befd6a786267c045ee82532759a7c214d7"

41 Locking and Unlocking Recipes Using bblock