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Date: Mon, 8 Nov 2021 16:05:31 -0800 From: Fangrui Song <maskray@...gle.com> To: Nick Desaulniers <ndesaulniers@...gle.com> Cc: Masahiro Yamada <masahiroy@...nel.org>, x86@...nel.org, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, "H . Peter Anvin" <hpa@...or.com>, clang-built-linux@...glegroups.com, Dave Hansen <dave.hansen@...ux.intel.com>, linux-kernel@...r.kernel.org, llvm@...ts.linux.dev Subject: Re: [PATCH 2/2] x86/purgatory: remove -nostdlib compiler flag On 2021-11-08, Nick Desaulniers wrote: >On Sun, Nov 7, 2021 at 8:27 AM Masahiro Yamada <masahiroy@...nel.org> wrote: >> >> The -nostdlib option requests the compiler to not use the standard >> system startup files or libraries when linking. It is effective only >> when $(CC) is used as a linker driver. > >Is that right? ld.lld recognizes --nostdlib and has --help text for it. GCC/Clang driver -nostdlib != ld.bfd/ld.lld -nostdlib. ld.lld -nostdlib just ignores SEARCH_DIR in a linker script. I think ld.bfd's -nostdlib is more complex than that which also has something to do with its internal linker script location. Anyway, getting of the obscure ld -nostdlib is a good idea. >> >> $(LD) is directly used for linking purgatory.{ro,chk} here, hence >> -nostdlib is unneeded. >> >> Signed-off-by: Masahiro Yamada <masahiroy@...nel.org> >> --- >> >> arch/x86/purgatory/Makefile | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile >> index 95ea17a9d20c..ae53d54d7959 100644 >> --- a/arch/x86/purgatory/Makefile >> +++ b/arch/x86/purgatory/Makefile >> @@ -16,7 +16,7 @@ CFLAGS_sha256.o := -D__DISABLE_EXPORTS >> >> # When linking purgatory.ro with -r unresolved symbols are not checked, >> # also link a purgatory.chk binary without -r to check for unresolved symbols. >> -PURGATORY_LDFLAGS := -e purgatory_start -nostdlib -z nodefaultlib >> +PURGATORY_LDFLAGS := -e purgatory_start -z nodefaultlib >> LDFLAGS_purgatory.ro := -r $(PURGATORY_LDFLAGS) >> LDFLAGS_purgatory.chk := $(PURGATORY_LDFLAGS) >> targets += purgatory.ro purgatory.chk >> -- >> 2.30.2 > >-- >Thanks, >~Nick Desaulniers
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