Re: [Qemu-devel] [PATCH] qapi: add 'query-target' command to return target arch/bit size

[Peter Maydell]

On 21 August 2012 11:05, Daniel P. Berrange <address@hidden> wrote:
> On Mon, Aug 20, 2012 at 04:48:24PM -0500, Anthony Liguori wrote:
>> "bits" is really ambiguous.  What it means in QEMU (specifically the
>> value you are returning) is probably not what you expect it to mean.
>
> My intent was to indicate the pointer word size for the architecture.
> eg 64 for x86_64, ppc64, etc, and 32 and i686, ppc, etc. Probably
> should have called it 'wordsize' or something like that

This is not the same as the physical address size...

> Hmm, when I looked at the header in my checkout it already
> *is* 64 or 32 as I'd expect for the architecture in question.
>
> $ grep PHYS_ADDR_BITS */config-target.mak
> alpha-softmmu/config-target.mak:TARGET_PHYS_ADDR_BITS=64
> arm-softmmu/config-target.mak:TARGET_PHYS_ADDR_BITS=64

...eg for ARM we have a 32 bit pointer size but 40 bit physical
addresses (on some cores) and we set TARGET_PHYS_ADDR_BITS
to 64 in all cases.

> i386-softmmu/config-target.mak:TARGET_PHYS_ADDR_BITS=64

i386 is the other obvious "pointers are 32 bit but we
set TARGET_PHYS_ADDR_BITS wider", for about the same reasons.

-- PMM