Re: [Qemu-devel] [PATCH 12/15] s390x: reduce TARGET_PHYS_ADDR_SPACE_BITS to 62

["Andreas Färber" <afaerber@suse.de>]

Am 27.05.2013 09:28, schrieb Paolo Bonzini:
> Il 26/05/2013 23:08, Christian Borntraeger ha scritto:
>> On 26/05/13 21:07, Paolo Bonzini wrote:
>>> Il 26/05/2013 16:14, Andreas Färber ha scritto:
>>>>> With the next patch, the memory API will complain if the
>>>>> TARGET_PHYS_ADDR_SPACE_BITS gets dangerously close to an
>>>>> overflow.  s390x can handle up to 64 bit of physical address
>>>>> space from its page tables, but we never use that much.  Just
>>>>> decrease the value.
>>>>>
>>>>> Cc: Alexander Graf <agraf@suse.de>
>>>>> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
[...]
>> I would prefer to allow 64bit of address space. Memory on s390x can be 
>> discontiguous. It is currently not used under KVM and it might not make
>> a lot of sense, but the current KVM code  would allow a guest that has a 
>> layout of lets say 0...1GB + 16EB-1GB...16EB. 
>>
>> Furthermore, I know of some (prototype only) hw memory devices that actually
>> populated the upper memory addresses. If such a thing becomes reality in the
>> future we cannot provide virtualization of those.
> 
> Ok, I'll drop this patch and the next one from the pull request.

It has already been merged, that's how I became aware of it:

http://git.qemu.org/?p=qemu.git;a=commit;h=fd469df97ab4277411ecdd4032a2f045a3a87b2a

Note that Alex is currently absent, so please CC some of the other s390x
folks or wait for an ack if you plan alternative changes.

Cheers,
Andreas

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