Re: [virtio-comment] Re: [PATCH v1] virtio-mem: minor clarification regarding read-access to unplugged blocks

[Cornelia Huck <cohuck@redhat.com>]

On Wed, 2 Dec 2020 10:25:16 +0100
David Hildenbrand <david@redhat.com> wrote:

> On 27.11.20 12:02, Cornelia Huck wrote:
> > On Fri, 27 Nov 2020 11:39:50 +0100
> > David Hildenbrand <david@redhat.com> wrote:
> >   
> >> On 20.11.20 16:13, Cornelia Huck wrote:  
> >>> On Mon, 16 Nov 2020 20:16:29 +0100
> >>> David Hildenbrand <david@redhat.com> wrote:
> >>>     
> >>>> Let's clarify that we don't expect all DMA to work with unplugged blocks.
> >>>> We really only give guarantees when reading from unplugged memory blocks
> >>>> via the CPU, e.g., as done by Linux when creating a system dump via
> >>>> kdump: the new kernel will copy the content of the old (crashed) kernel
> >>>> via the CPU to user space, from where it will find its final destination
> >>>> inside the dump file. Note that dumping via makedumpfile under Linux will
> >>>> avoid reading unplugged blocks completely.
> >>>>
> >>>> This is a preparation for device passthrough to VMs, whereby such
> >>>> dedicated devices might not be able to read from unplugged memory blocks.
> >>>>
> >>>> Let's document that this scenario is possible, and why this handling is
> >>>> in place at all.
> >>>>
> >>>> Cc: teawater <teawaterz@linux.alibaba.com>
> >>>> Cc: Marek Kedzierski <mkedzier@redhat.com>
> >>>> Cc: Michael S. Tsirkin <mst@redhat.com>
> >>>> Cc: Cornelia Huck <cohuck@redhat.com>
> >>>> Signed-off-by: David Hildenbrand <david@redhat.com>
> >>>> ---
> >>>>  virtio-mem.tex | 9 +++++++--
> >>>>  1 file changed, 7 insertions(+), 2 deletions(-)    
> >>>
> >>> Looks reasonable to me.
> >>>
> >>> Acked-by: Cornelia Huck <cohuck@redhat.com>    
> >>
> >> Thanks!
> >>
> >> I assume I'll need a github issue etc. to get this in, right?
> >>  
> > 
> > Yes; just open the issue, point to this patch in the archives, and
> > reply with the issue here.
> > 
> > (I don't think this is trivial enough to push without voting.)
> >   
> 
> Makes sense. I'll wait a bit more. Thanks!
> 

I think you can just go ahead and request a vote... no need to wait
further IMHO.


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