| Message ID | 1605520506-26733-1-git-send-email-yangtiezhu@loongson.cn (mailing list archive) |
|---|---|
| State | RFC |
| Headers | show |
| Series | [RFC,v2] MIPS: Kconfig: Select ARCH_WANT_FRAME_POINTERS | expand |
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 ? Thomas.
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
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig index ddaff19..4a4c791 100644 --- a/arch/mips/Kconfig +++ b/arch/mips/Kconfig @@ -15,6 +15,7 @@ config MIPS select ARCH_USE_QUEUED_RWLOCKS select ARCH_USE_QUEUED_SPINLOCKS select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU + select ARCH_WANT_FRAME_POINTERS select ARCH_WANT_IPC_PARSE_VERSION select BUILDTIME_TABLE_SORT select CLONE_BACKWARDS
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 think it is useful to get debugging information as described in the following texts: lib/Kconfig.debug config FRAME_POINTER bool "Compile the kernel with frame pointers" ... default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS help If you say Y here the resulting kernel image will be slightly larger and slower, but it gives very useful debugging information in case of kernel bugs. (precise oopses/stacktraces/warnings) Documentation/dev-tools/kgdb.rst This option inserts code into the compiled executable which saves the frame information in registers or on the stack at different points which allows a debugger such as gdb to more accurately construct stack back traces while debugging the kernel. Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn> --- v2: Update the commit message to correct the typo "to into" to "into" arch/mips/Kconfig | 1 + 1 file changed, 1 insertion(+)