Messages in this thread | | | Date | Tue, 9 Jun 2020 23:37:15 -0700 | From | Fangrui Song <> | Subject | Re: [kbuild-all] Re: gcc-5: error: -gz is not supported in this configuration |
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> But if that gcc was originally > _configured_ with a version of binutils that doesn't support -gz=zlib,
I agree with this theory :)
On 2020-06-10, Arvind Sankar wrote: >On Tue, Jun 09, 2020 at 11:23:31PM -0400, Arvind Sankar wrote: >> On Tue, Jun 09, 2020 at 11:12:25PM -0400, Arvind Sankar wrote: >> > The output of gcc-5 -dumpspecs may also be useful. >> > >> > The exact Kconfig check should have been >> > gcc-5 -Werror -gz=zlib -S -x c /dev/null -o /dev/null >> > >> > I can't see how that would succeed if the a.c test didn't but maybe just >> > in case? >> >> Oh wait, -S instead of -c. Which means it runs neither the assembler nor >> the linker, so gcc won't error out. But if that gcc was originally >> _configured_ with a version of binutils that doesn't support -gz=zlib, >> it will give an error on -c regardless of whether the runtime binutils >> would actually support it or not. > >I think the below might be better than passing the option via -Wa, since >gcc will translate -gz=zlib into the right assembler option anyway, and >it will also generate an error if the compiler driver was misconfigured >and won't support the option even if the rest of the toolchain does, >fixing the config dependency. > >Unless this doesn't work with Clang?
Clang>=6 supports -gz=zlib
>Alternatively (or even in addition), we should redefine cc-option to use >-c, it uses -S in the Kconfig version, apparently for speed, but -c in >the Kbuild version.
Unifying cc-option in scripts/Kbuild.include & scripts/Kconfig.include sounds good.
>diff --git a/Makefile b/Makefile >index 839f9fee22cb..cb29e56f227a 100644 >--- a/Makefile >+++ b/Makefile >@@ -842,7 +842,7 @@ endif > > ifdef CONFIG_DEBUG_INFO_COMPRESSED > DEBUG_CFLAGS += -gz=zlib >-KBUILD_AFLAGS += -Wa,--compress-debug-sections=zlib >+KBUILD_AFLAGS += -gz=zlib > KBUILD_LDFLAGS += --compress-debug-sections=zlib > endif > >diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug >index cb98741601bd..94ce36be470c 100644 >--- a/lib/Kconfig.debug >+++ b/lib/Kconfig.debug >@@ -229,7 +229,7 @@ config DEBUG_INFO_COMPRESSED > bool "Compressed debugging information" > depends on DEBUG_INFO > depends on $(cc-option,-gz=zlib) >- depends on $(as-option,-Wa$(comma)--compress-debug-sections=zlib) >+ depends on $(as-option,-gz=zlib) > depends on $(ld-option,--compress-debug-sections=zlib) > help > Compress the debug information using zlib. Requires GCC 5.0+ or Clang
This patch looks good.
(clang cc1as only supports(hardcodes) a limited number of -Wa, options (it parses the options by itself, rather than delegating to GNU as like GCC). If there is a compiler driver option, that is usually preferable)
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