Re: [PATCH v5] hostmem-file: add offset option

[Igor Mammedov]

On Wed, 5 Apr 2023 15:58:31 +0200
David Hildenbrand <david@redhat.com> wrote:

> On 04.04.23 16:36, Peter Xu wrote:
> > On Mon, Apr 03, 2023 at 10:14:21PM +0000, Alexander Graf wrote:  
> >> Add an option for hostmem-file to start the memory object at an offset
> >> into the target file. This is useful if multiple memory objects reside
> >> inside the same target file, such as a device node.
> >>
> >> In particular, it's useful to map guest memory directly into /dev/mem
> >> for experimentation.
> >>
> >> To make this work consistently, also fix up all places in QEMU that
> >> expect fd offsets to be 0.
> >>
> >> Signed-off-by: Alexander Graf <graf@amazon.com>  
> > 
> > Acked-by: Peter Xu <peterx@redhat.com>
> > 
> > I also agree it'll be nicer to split the fix into separate patch, though.
> > The only affected part IIUC is multi-process QEMU since 6.0.0.  Copying the
> > maintainers too so they'll be aware.
> > 
> > Corresponds to the tag:
> > 
> > Fixes: ed5d001916 ("multi-process: setup memory manager for remote device")
> >   
> 
> If there are no options on splitting out the fix, I'll route this via my 
> tree.

Having fixes as separate prep patch is much more preferable.

Another question is if we should also check that provided
offset honors 'align' option?