On Thu, 6 Oct 2016, James Hogan wrote:
> The native ABI vDSO linker script vdso.lds is built by preprocessing
> vdso.lds.S, with the native -mabi flag passed in to get the correct ABI
> definitions. Unfortunately however certain toolchains choke on -mabi=64
> without a corresponding compatible -march flag, for example:
>
> cc1: error: ʽ-march=mips32r2ʼ is not compatible with the selected ABI
> scripts/Makefile.build:338: recipe for target 'arch/mips/vdso/vdso.lds' failed
>
> Fix this by including ccflags-vdso in the KBUILD_CPPFLAGS for vdso.lds,
> which includes the appropriate -march flag.
>
> Fixes: ebb5e78cc634 ("MIPS: Initial implementation of a VDSO")
> Signed-off-by: James Hogan <james.hogan@xxxxxxxxxx>
> Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
> Cc: linux-mips@xxxxxxxxxxxxxx
> Cc: <stable@xxxxxxxxxxxxxxx> # 4.4.x-
> ---
Reviewed-by: Maciej W. Rozycki <macro@xxxxxxxxxx>
NB by default GCC is configured for the default of `-march=from-abi',
which is why saying `-mabi=64' only often works as such GCC implicitly
switches to a compatible `-march=' setting (i.e. `mips3' vs `mips1' for
o32). However when configured with `-march=' set to a particular ISA
level, such as `mips32r2' quoted above you need to select a compatible ISA
explicitly when switching to a 64-bit ABI (arguably you could configure
with `-march=mips64r2' instead as with a 32-bit ABI such a setting would
limit the instruction set to the 32-bit subset automatically).
Also I've noticed $(aflags-vdso) duplicate `-I' and `-E' options already
included with $(ccflags-vdso); I wonder if the duplicates should simply be
removed or whether $(cflags-vdso) ought to filter from $(KBUILD_CFLAGS)
and $(aflags-vdso) -- from $(KBUILD_AFLAGS) instead (or $(ccflags-vdso)
should just take the options from $(KBUILD_CPPFLAGS)). Also why `-E' is
supposed to take an argument? Can you please have a look at it?
Maciej
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