Subject: Re: [PATCH] kbuild: Add '-fms-extensions' to areas with dedicated CFLAGS

From: Nathan Chancellor <[email-masked]>
Date: Wed, 5 Nov 2025 13:15:22 -0700

On Wed, Nov 05, 2025 at 07:44:26AM -0600, Segher Boessenkool wrote:
> On Sat, Nov 01, 2025 at 12:35:47PM -0400, Nathan Chancellor wrote:
> > There are many places within the kernel that use their own CFLAGS
> > instead of the main KBUILD_CFLAGS, meaning code written with the main
> > kernel's use of '-fms-extensions' in mind that may be tangentially
> > included in these areas will result in "error: declaration does not
> > declare anything" messages from the compiler.
> 
> Please fix such non-standard code then, instead?  The only (documented)
> thing -fms-extensions does for C code is give meaning to something that
> otherwise is a syntax error (and it is for a good reason!)

Right, the kernel would like to start taking advantage of one of those
extensions. See these other threads for more information.

https://lore.kernel.org/[email-masked]/
https://lore.kernel.org/[email-masked]/

Cheers,
Nathan