Re: [PATCH] riscv: ftrace: select HAVE_BUILDTIME_MCOUNT_SORT

[Paul Walmsley <pjw@kernel.org>]

On Thu, 9 Apr 2026, cp0613@linux.alibaba.com wrote:

> From: Chen Pei <cp0613@linux.alibaba.com>
> 
> RISC-V already satisfies all prerequisites for build-time mcount sorting:
> the sorttable host tool handles EM_RISCV in its machine-type dispatch, and
> the __mcount_loc section entries are stored as direct virtual addresses in
> the final vmlinux binary, so no relocation processing is required during
> the sort step.
> 
> Select HAVE_BUILDTIME_MCOUNT_SORT so that BUILDTIME_MCOUNT_SORT is
> automatically enabled when DYNAMIC_FTRACE is configured.  This allows
> sorttable to sort the __mcount_loc section at link time, making the
> run-time ftrace initialisation path skip the software sort and reducing
> kernel startup overhead.
> 
> Verified with CONFIG_FTRACE_SORT_STARTUP_TEST=y, which confirms that
> the section produced by the build is already in ascending order:
> 
>   [    0.000000] ftrace section at ffffffff81015a60 sorted properly
> 
> Signed-off-by: Chen Pei <cp0613@linux.alibaba.com>

Thanks, queued for v7.2.


- Paul