Re: [PATCH 1/3] powerpc64: make clang cross-build friendly

[Naveen N Rao <naveen@kernel.org>]

On Mon, Dec 08, 2025 at 09:32:06PM +0530, Hari Bathini wrote:
> Thanks for the review, Naveen.
> 
> On 24/11/25 11:19 am, Naveen N Rao wrote:
> > On Sun, Nov 09, 2025 at 02:34:03AM +0530, Hari Bathini wrote:
> > > ARCH_USING_PATCHABLE_FUNCTION_ENTRY depends on toolchain support for
> > > -fpatchable-function-entry option. The current script that checks
> > > for this support only handles GCC. Rename the script and extend it
> > > to detect support for -fpatchable-function-entry with Clang as well,
> > > allowing clean cross-compilation with Clang toolchains.
> > > 
> > > Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
> > > ---
> > >   arch/powerpc/Kconfig                                         | 5 +++--
> > >   ...-function-entry.sh => check-fpatchable-function-entry.sh} | 0
> > >   2 files changed, 3 insertions(+), 2 deletions(-)
> > >   rename arch/powerpc/tools/{gcc-check-fpatchable-function-entry.sh => check-fpatchable-function-entry.sh} (100%)
> > > 
> > > diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> > > index 325c1171894d..dfb62e211c92 100644
> > > --- a/arch/powerpc/Kconfig
> > > +++ b/arch/powerpc/Kconfig
> > > @@ -568,8 +568,9 @@ config ARCH_USING_PATCHABLE_FUNCTION_ENTRY
> > >   	depends on FUNCTION_TRACER && (PPC32 || PPC64_ELF_ABI_V2)
> > >   	depends on $(cc-option,-fpatchable-function-entry=2)
> > >   	def_bool y if PPC32
> > > -	def_bool $(success,$(srctree)/arch/powerpc/tools/gcc-check-fpatchable-function-entry.sh $(CC) -mlittle-endian) if PPC64 && CPU_LITTLE_ENDIAN
> > > -	def_bool $(success,$(srctree)/arch/powerpc/tools/gcc-check-fpatchable-function-entry.sh $(CC) -mbig-endian) if PPC64 && CPU_BIG_ENDIAN
> > > +	def_bool $(success,$(srctree)/arch/powerpc/tools/check-fpatchable-function-entry.sh $(CC) -mlittle-endian) if PPC64 && CPU_LITTLE_ENDIAN && CC_IS_GCC
> > > +	def_bool $(success,$(srctree)/arch/powerpc/tools/check-fpatchable-function-entry.sh $(CC) -target ppc64le -mlittle-endian) if PPC64 && CPU_LITTLE_ENDIAN && CC_IS_CLANG
> > 
> > Can you instead pass $(CLANG_FLAGS) to retain the same command across
> > gcc/clang?
> 
> Should work, I guess.
> But do I need to test for any additional clang flags that
> may interfere with what we are trying to check here?

From what I can tell, $(CLANG_FLAGS) includes a fairly static set of 
flags which will be included alongside other $CFLAGS. So, I don't think 
anything special should be needed there.

- Naveen