Re: [PATCH 26/27] Enable 32bit dirty log pointers on 64bit host

[Avi Kivity <avi@redhat.com>]

On 09/29/2009 11:17 AM, Alexander Graf wrote:
>
> On 29.09.2009, at 11:14, Avi Kivity wrote:
>
>> On 09/29/2009 10:18 AM, Alexander Graf wrote:
>>> With big endian userspace, we can't quite figure out if a pointer
>>> is 32 bit (shifted>> 32) or 64 bit when we read a 64 bit pointer.
>>>
>>> This is what happens with dirty logging. To get the pointer interpreted
>>> correctly, I just make it bounce twice, but admittedly that is not
>>> ideal.
>>>
>>> I'm open for suggestions here.
>>>
>>>
>>
>> How about adding a new union member to struct kvm_dirty_log:
>>
>> __u64 dirty_bitmap_virt;
>
> And modifying userspace to write to that one?
>

Yes - old userspace will still build and work (we don't remove the old 
field) on little endian or BE32, new userspace will work on all 
flavours.  We need new userspace anyway to take advantage of dirty logging.

-- 
error compiling committee.c: too many arguments to function