Dan Horák <dan@xxxxxxxx> writes: > On Fri, 22 Jul 2022 22:32:06 +1000 > Michael Ellerman <michael@xxxxxxxxxxxxxx> wrote: >> Dan Horák <dan@xxxxxxxx> writes: >> > Commit d11219ad53dc disabled the DCN driver for all platforms that >> > define PPC64 due long build issues during "make allmodconfig" using >> > cross-compilation. Cross-compilation defaults to the ppc64_defconfig >> > and thus big-endian toolchain configuration. The ppc64le platform uses a >> > different ABI and doesn't suffer from the build issues. >> >> Unfortunately it's a bit messier than that. >> >> The build error occurs when the compiler is built to use a 64-bit long >> double type. >> >> The ppc64le ABI document says that long double should be 128-bits, but >> there are ppc64le compilers out there that are configured to use 64-bit >> long double, notably the kernel.org crosstool compilers. >> >> So just testing for CPU_LITTLE_ENDIAN means we'll still get build errors >> on those compilers. >> >> But I think we can detect the long double size and key off that. Can you >> test the patch below works for you? >> >> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig >> index 7aa12e88c580..e9f8cd50af99 100644 >> --- a/arch/powerpc/Kconfig >> +++ b/arch/powerpc/Kconfig >> @@ -281,6 +281,9 @@ config PPC >> # Please keep this list sorted alphabetically. >> # >> >> +config PCC_LONG_DOUBLE_128 >> + def_bool $(success,test "$(shell,echo __LONG_DOUBLE_128__ | $(CC) -E -P -)" = 1) > > ^^^ there is a typo s/PCC/PPC/ :-) Oops, renamed it after testing :} > with that fixed, it then defines AMD_DC_DCN on Fedora 36 with > gcc-12.1.1-1.fc36.ppc64le and we should be OK. Thanks. I'll send a proper patch. cheers
