diff options
Diffstat (limited to 'tools/buildman/README')
| -rw-r--r-- | tools/buildman/README | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/tools/buildman/README b/tools/buildman/README index 4705d26..26755c5 100644 --- a/tools/buildman/README +++ b/tools/buildman/README @@ -898,6 +898,48 @@ when using the -b flag. For example: will build commits in us-buildman that are not in upstream/master. +Building Faster +=============== + +By default, buildman executes 'make mrproper' prior to building the first +commit for each board. This causes everything to be built from scratch. If you +trust the build system's incremental build capabilities, you can pass the -I +flag to skip the 'make mproper' invocation, which will reduce the amount of +work 'make' does, and hence speed up the build. This flag will speed up any +buildman invocation, since it reduces the amount of work done on any build. + +One possible application of buildman is as part of a continual edit, build, +edit, build, ... cycle; repeatedly applying buildman to the same change or +series of changes while making small incremental modifications to the source +each time. This provides quick feedback regarding the correctness of recent +modifications. In this scenario, buildman's default choice of build directory +causes more build work to be performed than strictly necessary. + +By default, each buildman thread uses a single directory for all builds. When a +thread builds multiple boards, the configuration built in this directory will +cycle through various different configurations, one per board built by the +thread. Variations in the configuration will force a rebuild of affected source +files when a thread switches between boards. Ideally, such buildman-induced +rebuilds would not happen, thus allowing the build to operate as efficiently as +the build system and source changes allow. buildman's -P flag may be used to +enable this; -P causes each board to be built in a separate (board-specific) +directory, thus avoiding any buildman-induced configuration changes in any +build directory. + +U-Boot's build system embeds information such as a build timestamp into the +final binary. This information varies each time U-Boot is built. This causes +various files to be rebuilt even if no source changes are made, which in turn +requires that the final U-Boot binary be re-linked. This unnecessary work can +be avoided by turning off the timestamp feature. This can be achieved by +setting the SOURCE_DATE_EPOCH environment variable to 0. + +Combining all of these options together yields the command-line shown below. +This will provide the quickest possible feedback regarding the current content +of the source tree, thus allowing rapid tested evolution of the code. + + SOURCE_DATE_EPOCH=0 ./tools/buildman/buildman -I -P tegra + + Other options ============= |