Re: [RFC PATCH v2] MIPS: Kconfig: Select ARCH_WANT_FRAME_POINTERS

[Tiezhu Yang]

On 11/16/2020 11:14 PM, Thomas Bogendoerfer wrote:
> On Mon, Nov 16, 2020 at 05:55:06PM +0800, Tiezhu Yang wrote:
> > Select ARCH_WANT_FRAME_POINTERS to fix the following build error under
> > CONFIG_DEBUG_ATOMIC_SLEEP:
> >
> >    CC      arch/mips/kernel/signal.o
> > {standard input}: Assembler messages:
> > {standard input}:1775: Error: Unable to parse register name $fp
> > scripts/Makefile.build:283: recipe for target 'arch/mips/kernel/signal.o' failed
> > make[2]: *** [arch/mips/kernel/signal.o] Error 1
> > scripts/Makefile.build:500: recipe for target 'arch/mips/kernel' failed
> > make[1]: *** [arch/mips/kernel] Error 2
> > Makefile:1799: recipe for target 'arch/mips' failed
> > make: *** [arch/mips] Error 2
> I don't see this error and to me it looks strange to fix that with
> enablding frame pointers... What gcc is this ?

I found this build error used with gcc 4.9.4.
I try it used with gcc 7.3.1 and it has no problem.
We can use new gcc version to avoid this build error.

Additionally, I want to know whether ARCH_WANT_FRAME_POINTERS
is necessary for MIPS to get more debugging info, with this
config we can enable the config FRAME_POINTER by default and
disable it manually.

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Makefile#n790
ifdef CONFIG_FRAME_POINTER
KBUILD_CFLAGS   += -fno-omit-frame-pointer -fno-optimize-sibling-calls

Thanks,
Tiezhu