On Sun, Jun 14, 2020 at 11:43:41PM +0900, Masahiro Yamada wrote: > cc-option and as-option are almost the same; both pass the flag to > $(CC). The main difference is the cc-option stops before the assemble > stage (-S option) whereas as-option stops after it (-c option). > > I chose -S because it is slightly faster, but $(cc-option,-gz=zlib) > returns a wrong result (https://lkml.org/lkml/2020/6/9/1529). > It has been fixed by a separate patch, but using -c is more robust. > > However, you cannot simply replace -S with -c because the following > code would break: > > depends on $(cc-option,-gsplit-dwarf) > > The combination of -c and -gsplit-dwarf does not accept /dev/null as > output. > > $ cat /dev/null | gcc -gsplit-dwarf -S -x c - -o /dev/null > $ echo $? > 0 > > $ cat /dev/null | gcc -gsplit-dwarf -c -x c - -o /dev/null > objcopy: Warning: '/dev/null' is not an ordinary file > $ echo $? > 1 > > $ cat /dev/null | gcc -gsplit-dwarf -c -x c - -o tmp.o > $ echo $? > 0 > > There is another flag that creates an separate file based on the > object file path: > > $ cat /dev/null | gcc -ftest-coverage -c -x c - -o /dev/null > <stdin>:1: error: cannot open /dev/null.gcno > > So, we cannot use /dev/null to sink the output. > > Align the cc-option implementation with scripts/Kbuild.include. > > With -c option used in cc-option, as-option is unneeded. > > Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx> > --- > > arch/arm64/Kconfig | 2 +- > lib/Kconfig.debug | 1 - > scripts/Kconfig.include | 8 +------- > 3 files changed, 2 insertions(+), 9 deletions(-) > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 31380da53689..6eb18f45258e 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -1564,7 +1564,7 @@ config CC_HAS_SIGN_RETURN_ADDRESS > def_bool $(cc-option,-msign-return-address=all) > > config AS_HAS_PAC > - def_bool $(as-option,-Wa$(comma)-march=armv8.3-a) > + def_bool $(cc-option,-Wa$(comma)-march=armv8.3-a) For this arm64 part: Acked-by: Will Deacon <will@xxxxxxxxxx> Will
