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

[Nikolay Nikolaev]

On Wed, Jun 25, 2014 at 9:07 PM, Michael S. Tsirkin <address@hidden> wrote:
> On Wed, Jun 25, 2014 at 07:56:46PM +0300, Nikolay Nikolaev wrote:
>> 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?
>> The vring addresses are QEMU UA addresses. Of course vhost-user can
>> translate them to guest physical before sending the message.
>
> It seems useful to have them as QEMU UA, this will allow
> frontends other than virtio where QEMU operates the
> ring.

OK - so there will be a new offset field. That's fine with me. What
would be the deadline for such change?
It's not exactly bugfix. On the other hand there's no wide adoption of
the protocol so it's still not critical to change it.

>
>> > perhaps the offset can replace the ua).
>> >
>> >> 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