On Fri, Nov 06, 2015 at 09:55:54AM -0800, Shi, Yang wrote:
On 11/6/2015 9:51 AM, Catalin Marinas wrote:
On Fri, Nov 06, 2015 at 09:39:07AM -0800, Shi, Yang wrote:
On 11/6/2015 9:35 AM, Catalin Marinas wrote:
On Fri, Nov 06, 2015 at 09:23:38AM -0800, Shi, Yang wrote:
On 11/6/2015 8:25 AM, Will Deacon wrote:
However, the patch would allow one to disable FRAME_POINTERS (not sure it has any effect on the aarch64 gcc though).
No, it doesn't. Actually, FRAME_POINTER could be disabled regardless of the patch.
In which case I suggest that we always select it just as a clearer statement that the feature cannot be disabled (and you never know what the compiler people decide to do in the future).
Do you mean select FRAME_POINTER in ARCH_WANT_FRAME_POINTERS?
Yes, we could, but this may cause other architectures which select ARCH_WANT_FRAME_POINTERS to have FRAME_POINTER selected too.
This would have been the ideal option, something like:
--- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -322,7 +322,7 @@ config ARCH_WANT_FRAME_POINTERS help
config FRAME_POINTER
- bool "Compile the kernel with frame pointers"
- bool "Compile the kernel with frame pointers" if !ARCH_WANT_FRAME_POINTERS depends on DEBUG_KERNEL && \ (CRIS || M68K || FRV || UML || \ AVR32 || SUPERH || BLACKFIN || MN10300 || METAG) || \
But, as you said, we would need to check the other architectures selecting ARCH_WANT_FRAME_POINTERS.
How about:
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 1d1521c..709255a 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -319,6 +319,7 @@ config DEBUG_SECTION_MISMATCH # config ARCH_WANT_FRAME_POINTERS bool
select FRAME_POINTER if ARM64 helpconfig FRAME_POINTER
If other architectures want the same behavior, they could easily append to the is statement. If all arches which selects ARCH_WANT_FRAME_POINTERS, the if statement could be just removed.
I prefer the select in the ARM64 Kconfig entry as below:
--- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -27,6 +27,7 @@ config ARM64 select CPU_PM if (SUSPEND || CPU_IDLE) select DCACHE_WORD_ACCESS select EDAC_SUPPORT
- select FRAME_POINTER select GENERIC_ALLOCATOR select GENERIC_CLOCKEVENTS select GENERIC_CLOCKEVENTS_BROADCAST