Re: [Qemu-devel] [PATCH 00/19] multi-arch+linux-user: Cleanup ELF_MACHINE

[Paolo Bonzini <pbonzini@redhat.com>]

On 16/08/2015 01:28, Peter Crosthwaite wrote:
> Every arch defines ELF_MACHINE in cpu.h to an arch-specific value. This
> definition is rarely needed by core code (only in a few cases). It
> conflicts with the multi-arch effort where cpu.h cannot export cpu
> specifics via macros like this. So remove ELF_MACHINE completely from
> all the cpu.h's.
> 
> Linux-user defines both ELF_ARCH and ELF_MACHINE, but for most cases
> they are the same. So provide a default of ELF_MACHINE == ELF_ARCH to
> handle most cases and just minimally define ELF_MACHINE locally in
> linux-user where there is a genuine difference.
> 
> While touching the code cleanup elf_check_arch in linux-user with
> a similar default-based system to minimise the boiler-plate for arch
> EM_ code.
> 
> Then go arch-by-arch to remove ELF_MACHINE from cpu.h. For many arches
> this causes the ELF_MACHINE == ELF_ARCH default to kick in. Some arches
> need their bootloader usages of ELF_MACHINE converted to use EM_FOO
> directly.
> 
> Alpha is unique, in that ELF_MACHINE is completely unused by existing
> code.
> 
> i386 and ppc are the most complex, where there is a genuine need to
> switch ELF_MACHINE depending on the target sub-arch. In these cases
> ELF_MACHINE if prefixed to be target specific. This will need further
> rethinking to get multi-arch support for those two arches.
> 
> There is an argument for keeping the per-arch definitions of the EM,
> but the correct place for this would be as virtual field in the QOM
> CPU class. Given the refactorings of the series this new field would
> be initially unused until we have the notion of a generic system mode
> bootloader or refactor linux-user boot to be more QOMified. So leaving
> the defs deleted for the moment for later revival.
> 
> Regards,
> Peter
> 
> Peter Crosthwaite (19):
>   linux_user: elfload: Default ELF_MACHINE to ELF_ARCH
>   linux-user: elfload: Provide default for elf_check_arch
>   arm: Remove ELF_MACHINE from cpu.h
>   mb: Remove ELF_MACHINE from cpu.h
>   m68k: Remove ELF_MACHINE from cpu.h
>   cris: Remove ELF_MACHINE from cpu.h
>   moxie: Remove ELF_MACHINE from cpu.h
>   unicore: Remove ELF_MACHINE from cpu.h
>   lm32: Remove ELF_MACHINE from cpu.h
>   or32: Remove ELF_MACHINE from cpu.h
>   tricore: Remove ELF_MACHINE from cpu.h
>   xtensa: Remove ELF_MACHINE from cpu.h
>   sh4: Remove ELF_MACHINE from cpu.h
>   s390: Remove ELF_MACHINE from cpu.h
>   sparc: Remove ELF_MACHINE from cpu.h
>   mips: Remove ELF_MACHINE from cpu.h
>   alpha: Remove ELF_MACHINE from cpu.h
>   i386: Rename ELF_MACHINE to be x86 specific
>   ppc: Rename ELF_MACHINE to be PPC specific
> 
>  hw/arm/armv7m.c                |  2 +-
>  hw/cris/boot.c                 |  2 +-
>  hw/i386/multiboot.c            |  2 +-
>  hw/lm32/lm32_boards.c          |  4 ++--
>  hw/lm32/milkymist.c            |  2 +-
>  hw/m68k/an5206.c               |  2 +-
>  hw/m68k/dummy_m68k.c           |  2 +-
>  hw/m68k/mcf5208.c              |  2 +-
>  hw/microblaze/boot.c           |  4 ++--
>  hw/mips/mips_fulong2e.c        |  2 +-
>  hw/mips/mips_malta.c           |  2 +-
>  hw/mips/mips_mipssim.c         |  2 +-
>  hw/mips/mips_r4k.c             |  2 +-
>  hw/moxie/moxiesim.c            |  2 +-
>  hw/openrisc/openrisc_sim.c     |  2 +-
>  hw/ppc/e500.c                  |  2 +-
>  hw/ppc/mac_newworld.c          |  4 ++--
>  hw/ppc/mac_oldworld.c          |  4 ++--
>  hw/ppc/ppc440_bamboo.c         |  2 +-
>  hw/ppc/prep.c                  |  2 +-
>  hw/ppc/spapr.c                 |  4 ++--
>  hw/ppc/virtex_ml507.c          |  2 +-
>  hw/s390x/ipl.c                 |  4 ++--
>  hw/sparc/leon3.c               |  2 +-
>  hw/sparc/sun4m.c               |  4 ++--
>  hw/sparc64/sun4u.c             |  4 ++--
>  hw/tricore/tricore_testboard.c |  2 +-
>  hw/xtensa/sim.c                |  4 ++--
>  hw/xtensa/xtfpga.c             |  2 +-
>  linux-user/elfload.c           | 37 +++++++++++--------------------------
>  target-alpha/cpu.h             |  2 --
>  target-arm/cpu.h               |  2 --
>  target-cris/cpu.h              |  2 --
>  target-i386/cpu.h              |  4 ++--
>  target-lm32/cpu.h              |  2 --
>  target-m68k/cpu.h              |  2 --
>  target-microblaze/cpu.h        |  2 --
>  target-mips/cpu.h              |  2 --
>  target-moxie/cpu.h             |  2 --
>  target-openrisc/cpu.h          |  1 -
>  target-ppc/cpu.h               |  4 ++--
>  target-s390x/cpu.h             |  1 -
>  target-sh4/cpu.h               |  2 --
>  target-sparc/cpu.h             |  6 ------
>  target-tricore/cpu.h           |  2 --
>  target-unicore32/cpu.h         |  2 --
>  target-xtensa/cpu.h            |  1 -
>  47 files changed, 53 insertions(+), 99 deletions(-)
> 

Peter, I suggest that you send a pull request yourself for this and the
Moxie change.

Paolo