Re: [PATCH] bitbake.conf: add BB_NUMBER_THREADS to BB_HASHEXCLUDE_COMMON

[Richard Purdie <richard.purdie@linuxfoundation.org>]

On Mon, 2022-02-28 at 09:42 +0100, Rasmus Villemoes wrote:
> The imx-gpu-sdk recipe in the meta-imx layer references
> ${BB_NUMBER_THREADS} in its do_compile function. Changing
> BB_NUMBER_THREADS between bitbake invocations leads to the well-known
> 
>   When reparsing ...meta-imx/meta-sdk/recipes-graphics/imx-gpu-sdk/imx-gpu-sdk_5.8.0.bb:do_compile, the basehash value changed from 69be88cf220840ff2203e11cfe65681880b0bf9b88db67d50c1ba772b883bd18 to 5e6d5029fac8d7856ada4c2eca359568298f82cdb64567d7dd4deda503d9f83a. The metadata is not deterministic and this needs to be fixed.
> 
> And I'm not the first to hit this problem with that recipe:
> https://community.nxp.com/t5/i-MX-Processors/imx-gpu-sdk-compile-error-IMX8MP-IMX8MM-IMX8MQ/td-p/1217864
> 
> This happens because BB_NUMBER_THREADS is in BB_HASHCONFIG_IGNORE_VARS,
> so changing it does not cause the recipe to be reparsed, but it is not
> included in BB_HASHEXCLUDE_COMMON and thus
> BB_BASEHASH_IGNORE_VARS. This is inconsistent with and in contrast to
> both PARALLEL_MAKE and OMP_NUM_THREADS, the latter of which even has
> ${BB_NUMBER_THREADS} as default value.

Technically imx-gpu-sdk is incorrect. BB_NUMBER_THREADS is the number of tasks
bitbake should run. PARALLEL_MAKE is what is used for parallelism in do_compile.

I appreciate that has -j in but you can use: ${@oe.utils.parallel_make(d)} to
obtain the value that recipe needs.

Cheers,

Richard