Re: [Qemu-devel] vhost-user: broken mem regions

[Nikolay Nikolaev]

On Wed, Jun 25, 2014 at 7:44 PM, Paolo Bonzini <address@hidden> wrote:
>> nregions: 4
>> region:
>>       gpa = 0x100000000
>>       size = 3221225472
>>       ua = 0x2aab6ac00000
>
> High memory, above 3 gigabytes.
>
>> region:
>>       gpa = 0xFFFC0000
>>       size = 262144
>>       ua = 0x7fc13d200000
>
> This is the BIOS.  There shouldn't be any FD for this one, it
> is not allocated in hugetlbfs.
>
>> region:
>>       gpa = 0x0
>>       size = 655360
>>       ua = 0x2aaaaac00000
>> region:
>>       gpa = 0xC0000
>>       size = 3220439040
>>       ua = 0x2aaaaacc0000
>
> Together, it's the first 3 GB of memory.
>
> I understand now what you mean.  Yeah, the format should be changed
> to include the offset (why does vhost-user need the ua at all?
> perhaps the offset can replace the ua).

I am trying to do the math here. So if this file is mapped by QEMU
into a single file then probably
(region[4].ua - region[3].ua) should give you the offset. And also
(region[4].ua - region[1].ua) shoudl give the above 3G offset. Or I am
missing something?



>
>> BTW Any idea what to do with region 2, it doesn’t look like the one belonging
>> to the same place, but qemu_get_ram_fd() returns same FD for it.
>
> This must be a bug.  I would have expected qemu_get_ram_fd to return -1
> here, so no descriptor should be passed to vhost-user.
>
> Paolo