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Re: [Qemu-devel] [PATCH 2/2] postcopy: Require RAMBlocks that are whole
From: |
Peter Xu |
Subject: |
Re: [Qemu-devel] [PATCH 2/2] postcopy: Require RAMBlocks that are whole pages |
Date: |
Fri, 19 May 2017 12:00:48 +0800 |
User-agent: |
Mutt/1.5.24 (2015-08-30) |
On Thu, May 18, 2017 at 09:08:34AM +0100, Dr. David Alan Gilbert wrote:
> * Juan Quintela (address@hidden) wrote:
> > "Dr. David Alan Gilbert (git)" <address@hidden> wrote:
> > > From: "Dr. David Alan Gilbert" <address@hidden>
> > >
> > > It turns out that it's legal to create a VM with RAMBlocks that aren't
> > > a multiple of the pagesize in use; e.g. a 1025M main memory using
> > > 2M host pages. That breaks postcopy's atomic placement of pages,
> > > so disallow it.
> > >
> > > Signed-off-by: Dr. David Alan Gilbert <address@hidden>
> >
> > Reviewed-by: Juan Quintela <address@hidden>
>
> Thanks
>
> > > }
> > >
> > > /* We don't support postcopy with shared RAM yet */
> > > - if (qemu_ram_foreach_block(test_range_shared, NULL)) {
> > > + if (qemu_ram_foreach_block(test_ramblock_postcopiable, NULL)) {
> >
> > When I was looking at this code, I still don't know why
> > qemu_ram_foreach_block() don't pass the block directly. It needs it
> > almost all callers.
> >
> > When I saw it I was about to change it, but got sidetracked on other
> > things :-p
>
> I think originally it passed very little information at all, and
> that RAMBlocks were these mystical things no one outside exec.c
> was really supposed to know about.
(Yeah I got the same question before. That's why I got
RAMBLOCK_FOREACH() but didn't use qemu_ram_foreach_block() since I
need at least page size info for the block...)
--
Peter Xu