[PATCH v3 07/11] lib: vsprintf: enable '%pbl' format specifier

[Lukas Funke]

Hi Tom,

On 18.01.2024 21:22, Tom Rini wrote:
> On Wed, Jan 10, 2024 at 10:10:33AM +0100, lukas.funke-oss at weidmueller.com wrote:
> 
>> From: Lukas Funke <lukas.funke at weidmueller.com>
>>
>> The commit enables vsprintf() to handle the '%pbl' format specifier
>> in order to print bitmaps and its derivatives such as cpumask and
>> nodemask [1]. This can be used to derive kernel boot parameters from
>> bitmaks such as 'isolcpu' or 'nohz_full' [2].
>>
>> [1] https://www.kernel.org/doc/Documentation/printk-formats.txt
>> [2] https://www.kernel.org/doc/html/latest/admin-guide/kernel-parameters.html
>>
>> Signed-off-by: Lukas Funke <lukas.funke at weidmueller.com>
> 
> This breaks building ARC platforms, and possibly others.  Note that
> tools/buildman/buildman is happy to fetch toolchains for you, and in
> this case it's also just the current kernel.org cross-toolchain. Please
> see https://docs.u-boot.org/en/latest/develop/ci_testing.html about how
> to trigger a CI run prior to sending v4, thanks.
> 

Thanks for the input. I ran the pipeline on github and it failed for 
riscv, m86k, x86_64. The reason is the missing 'find_next_zero_bit()' 
implementation (actually it's faulty on x86_64). What is a good way to 
cope with this problem? My suggestions would be:

- Add a generic 'find_next_zero_bit()'. This would be the
'Linux way' and requires refactoring of the bitops header.
- Add ifdef-macro/kconfig to only enable the format specifier only for 
the supported platforms. This would be the 'quick way'.

What would be your or the maintainers preferred solution?

Best regards
Lukas