[U-Boot] [PATCH V2] buildman: allow more incremental building

[Stephen Warren <swarren@wwwdotorg.org>]

On 04/11/2016 10:48 AM, Stephen Warren wrote:
> From: Stephen Warren <swarren@nvidia.com>
>
> One use-case for buildman is to continually run it interactively after
> each small step in a large refactoring operation. This gives more
> immediate feedback than making a number of commits and then going back and
> testing them. For this to work well, buildman needs to be extremely fast.
> At present, a couple issues prevent it being as fast as it could be:
>
> 1) Each time buildman runs "make %_defconfig", it runs "make mrproper"
> first. This throws away all previous build results, requiring a
> from-scratch build. Optionally avoiding this would speed up the build, at
> the cost of potentially causing or missing some build issues.
>
> 2) A build tree is created per thread rather than per board. When a thread
> switches between building different boards, this often causes many files
> to be rebuilt due to changing config options. Using a separate build tree
> for each board would avoid this. This does put more strain on the system's
> disk cache, but it is worth it on my system at least.
>
> This commit adds two command-line options to implement the changes
> described above; -I ("--incremental") turns of "make mrproper" and -P
> ("--per-board-out-dir") creats a build directory per board rather than per
> thread.
>
> Tested:
>
>      ./tools/buildman/buildman.py tegra
>      ./tools/buildman/buildman.py -I -P tegra
>      ./tools/buildman/buildman.py -b tegra_dev tegra
>      ./tools/buildman/buildman.py -b tegra_dev -I -P tegra
>
> ... each once after deleting the buildman result/work directory, and once
> "incrementally" after a previous identical invocation.
>
> Signed-off-by: Stephen Warren <swarren@nvidia.com>
> Reviewed-by: Tom Rini <trini@konsulko.com>
> Acked-by: Simon Glass <sjg@chromium.org> # v1
> Tested-by: Simon Glass <sjg@chromium.org> # v1
> ---
> v2: Add README updates.

Simon, does this version look good?