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Re: [Qemu-devel] [PATCH 2/2] postcopy: Require RAMBlocks that are whole
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH 2/2] postcopy: Require RAMBlocks that are whole pages |
Date: |
Thu, 18 May 2017 09:08:34 +0100 |
User-agent: |
Mutt/1.8.2 (2017-04-18) |
* 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.
Dave
> Later, Juan.
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK