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Re: [Qemu-devel] [PATCH 4/4] xen: Always set the vram dirty during migra
From: |
Stefano Stabellini |
Subject: |
Re: [Qemu-devel] [PATCH 4/4] xen: Always set the vram dirty during migration. |
Date: |
Fri, 20 Jul 2012 16:47:16 +0100 |
User-agent: |
Alpine 2.02 (DEB 1266 2009-07-14) |
On Fri, 20 Jul 2012, Anthony PERARD wrote:
> On 17/07/12 19:30, Stefano Stabellini wrote:
> > On Tue, 17 Jul 2012, Stefano Stabellini wrote:
> >> On Tue, 17 Jul 2012, Anthony PERARD wrote:
> >>> Because the call to track the dirty bit in the video ram during migration
> >>> won't
> >>> work (it returns -1), we set dirtybit on the all video ram.
> >>>
> >>> Signed-off-by: Anthony PERARD <address@hidden>
> >>> ---
> >>> xen-all.c | 5 +++++
> >>> 1 files changed, 5 insertions(+), 0 deletions(-)
> >>>
> >>> diff --git a/xen-all.c b/xen-all.c
> >>> index 498883b..00bdb50 100644
> >>> --- a/xen-all.c
> >>> +++ b/xen-all.c
> >>> @@ -502,6 +502,11 @@ static void xen_sync_dirty_bitmap(XenIOState *state,
> >>> return;
> >>> }
> >>>
> >>> + if (unlikely(xen_in_migration)) {
> >>> + /* track_dirty_vram does not work during migration */
> >>> + memory_region_set_dirty(framebuffer, 0, size);
> >>> + return;
> >>> + }
> >>> rc = xc_hvm_track_dirty_vram(xen_xc, xen_domid,
> >>> start_addr >> TARGET_PAGE_BITS, npages,
> >>> bitmap);
> >>
> >> Why are you setting the entire framebuffer dirty?
> >> We should set dirty only the actualy region that is supposed to be
> >> dirty.
>
> I set the dirty bit on the all framebuffer because the track dirty call
> fail, so I don't which bits are dirty. This one is for QEMU to know
> which part of the screen need to be updated.
In that case it would be better to set the entire bitmap to 0xff in case
xc_hvm_track_dirty_vram fails, right?
So that we don't need to special case live migration.