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Re: [PATCH 2/2] Remove vestiges of NaCl port from ARM assembly files.
On Sat, 20 May 2017, Matt Turner wrote:
> > (There are several other defines in sysdeps/arm/nacl/arm-features.h that
> > are never defined for non-NaCl, or have constant definitions for non-NaCl
> > - ARM_ALWAYS_BX, ARM_BX_ALIGN_LOG2, ARM_NO_INDEX_REGISTER - and which
> > should probably be cleaned up as well eventually in separate patches, but
> > the sfi_* are by far the most invasive. ARM_ASSUME_NO_IWMMXT is only
> > defined for NaCl at present, but logically could be defined for all builds
> > for ARMv6 and later (__ARM_ARCH >= 6, given GCC 4.8 or later or the
> > __ARM_ARCH emulation in sysdep.h) as iWMMXt is only on certain v5TE
> > processors. NO_THUMB is more complicated in that only NaCl defines it in
> > arm-features.h, but some individual .S files define it as well.)
>
> Some Marvell CPUs have iwMMXt, like the one in the OLPC XO 1.75. It's am
> ARMv7.
Thanks for the information - I was going based on what GCC knows about
CPUs with iwMMXt. ARMv8 removes the generic coprocessor specification,
only allowing coprocessor instructions with certain ARM-defined
coprocessor numbers, so I presume we can consider iwMMXt to be inherently
incompatible with the v8 architecture, and so define ARM_ASSUME_NO_IWMMXT
when building for 32-bit ARMv8.
--
Joseph S. Myers
joseph@codesourcery.com