[Consult] blackfin: About one building break issue for STACKTRACE

From: Chen Gang
Date: Thu Apr 16 2015 - 11:21:58 EST


Hello Maintainers:

I want to consult one building issue about blackfin, the related issue
is:

CC arch/blackfin/kernel/stacktrace.o
arch/blackfin/kernel/stacktrace.c: In function 'save_stack_trace':
arch/blackfin/kernel/stacktrace.c:23:6: error: frame pointer required, but reserved
void save_stack_trace(struct stack_trace *trace)
^
arch/blackfin/kernel/stacktrace.c:13:24: note: for 'current_frame_pointer'
register unsigned long current_frame_pointer asm("FP");
^

For me:

- Originally, I treated it as gcc's issue, but after think of, for me,
gcc is OK:

"-fomit-frame-pointer" is needed by extern "FP" pointer.

"-fomit-frame-pointer" is against "-pg" (they can not be together).

- For kernel:

STACKTRACE needs "-fomit-frame-pointer", and FUNCTION_TRACER will
enable "-pg",

FUNCTION_TRACER and STACKTRACE are related.

The related commit: "1c873be Blackfin: initial support for ftrace"
(the commit time point is Jun 9 2009).

- After this related commit, it never can pass building by upstream
blackfin gcc5:

make defconfig && make menuconfig

enable FUNCTION_TRACER (which also enable STACKTRACE)

make (which will cause building break)

So I want to consult:

- Is it OK to use upstream gcc5 for blackfin? (or which gcc version is
suitable for building blackfin Linux kernel?)

- Did the original commit pass building ? (e.g. by one of old gcc
version).

- How to fix this issue, next?


Welcome any members ideas, suggestions and completions.

Thanks.
--
Chen Gang

Open, share, and attitude like air, water, and life which God blessed
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