Re: [PATCH] scripts: headers_install.sh: Normalize __ASSEMBLY__ to __ASSEMBLER__

[Thomas Weißschuh]

Hi Thomas,

On 2026-07-16 12:24:07+0200, Thomas Huth wrote:
> On 09/03/2026 16.58, Thomas Weißschuh wrote:
> > There is an ongoing effort to replace the usage of __ASSEMBLER__ with
> > __ASSEMBLY__ throughout the kernel tree, see for example
> > commit 287d163322b7 ("arm64: Replace __ASSEMBLY__ with __ASSEMBLER__ in
> > non-uapi headers"). The latter is automatically provided by all compilers
> > and preprocessors supported by the kernel, so the explicit definitions
> > of __ASSEMBLER__ can be removed.
> > 
> > However the UAPI headers might be used with older (< GCC 3.0) or
> > non-GCC-compatible compilers, which do not define __ASSEMBLY__
> > automatically.
> 
> I just had a try with gcc 2.95.4 from a Debian Woody installation, and it
> defines __ASSEMBLER__ automatically when compiling *.S files, i.e. gcc 2.95
> does not seem to be a problem. So can you point me to a real case where
> someone tried to use a user space compiler where __ASSEMBLER__ was not
> defined automatically? Otherwise, I think this patch could be reverted
> again.

I don't have a specific case I can point you to. My goal was
consistency. Therefore I am against reverting the patch as long as
both __ASSEMBLER__ and __ASSEMBLY__ are used in the UAPI headers.
If we want to switch to __ASSEMBLER__ for the UAPI headers today,
we should instead invert the logic of this patch to consistently use it
everywhere. After all UAPI headers are migrated, the normalization can
then be removed.


Thomas

> > So this migration may brake users.
> > Also during the migration phase, the UAPI headers will use a mix of
> > *both* __ASSEMBLY__ and __ASSEMBLER__ at the same time, which is ugly.
> > 
> > For now make sure that the exported UAPI headers consistently use
> > __ASSEMBLER__ as before.
> > 
> > Link: https://lore.kernel.org/lkml/164baf81-2824-4943-bbc1-4ae8a160c0cc@xxxxxxxx/
> > Signed-off-by: Thomas Weißschuh <linux@xxxxxxxxxxxxxx>
> > ---
> > This should go either through kbuild or asm-generic, I think.
> > ---
> >   scripts/headers_install.sh | 1 +
> >   1 file changed, 1 insertion(+)
> > 
> > diff --git a/scripts/headers_install.sh b/scripts/headers_install.sh
> > index 9c15e748761c..2f1d1767ca26 100755
> > --- a/scripts/headers_install.sh
> > +++ b/scripts/headers_install.sh
> > @@ -36,6 +36,7 @@ sed -E -e '
> >   	s/(^|[^a-zA-Z0-9])__packed([^a-zA-Z0-9_]|$)/\1__attribute__((packed))\2/g
> >   	s/(^|[[:space:](])(inline|asm|volatile)([[:space:](]|$)/\1__\2__\3/g
> >   	s@#(ifndef|define|endif[[:space:]]*/[*])[[:space:]]*_UAPI@#\1 @
> > +	s/__ASSEMBLY__/__ASSEMBLER__/g
> >   ' $INFILE > $TMPFILE || exit 1
> >   scripts/unifdef -U__KERNEL__ -D__EXPORTED_HEADERS__ $TMPFILE > $OUTFILE
>