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Re: [Qemu-devel] [PATCH] xen: avoid tracking the region 0xa0000 - 0xbfff
From: |
Stefano Stabellini |
Subject: |
Re: [Qemu-devel] [PATCH] xen: avoid tracking the region 0xa0000 - 0xbffff |
Date: |
Tue, 14 Jun 2011 12:48:03 +0100 |
User-agent: |
Alpine 2.00 (DEB 1167 2008-08-23) |
On Tue, 14 Jun 2011, Alexander Graf wrote:
> On 03.06.2011, at 17:56, <address@hidden> <address@hidden> wrote:
>
> > From: Stefano Stabellini <address@hidden>
> >
> > Xen can only do dirty bit tracking for one memory region, so we should
> > explicitly avoid trying to track the legacy VGA region between 0xa0000
> > and 0xbffff, rather than trying and failing.
> >
> > Signed-off-by: Stefano Stabellini <address@hidden>
> > ---
> > xen-all.c | 4 ++++
> > 1 files changed, 4 insertions(+), 0 deletions(-)
> >
> > diff --git a/xen-all.c b/xen-all.c
> > index 9a5c3ec..1fdc2e8 100644
> > --- a/xen-all.c
> > +++ b/xen-all.c
> > @@ -218,6 +218,10 @@ static int xen_add_to_physmap(XenIOState *state,
> > if (get_physmapping(state, start_addr, size)) {
> > return 0;
> > }
> > + /* do not try to map legacy VGA memory */
> > + if (start_addr >= 0xa0000 && start_addr + size <= 0xbffff) {
>
> I don't quite like the hardcoded range here. What exactly is the issue? The
> fact that you can only map a single region? Then do a counter and fail when
> it's > 1.
That is what we were doing before: succeeding the first time and
failing from the second time on.
By "coincidence" the second time was the range 0xa0000-0xbffff so
everything worked as expected, but it wasn't obvious why.
I am just trying to make sure that one year from now it will be clear
just looking at the code why it works.
> If you don't want to map the VGA region as memory slot, why not change the
> actual mapping code in the cirrus adapter?
Because I didn't want to introduce any ugly if (xen_enable()) in generic
code, if it is that simple to catch the issue from xen specific code.
- [Qemu-devel] [PATCH] xen: avoid tracking the region 0xa0000 - 0xbffff, stefano.stabellini, 2011/06/03
- Message not available
- Re: [Qemu-devel] [PATCH] xen: avoid tracking the region 0xa0000 - 0xbffff,
Stefano Stabellini <=
- Re: [Qemu-devel] [PATCH] xen: avoid tracking the region 0xa0000 - 0xbffff, Alexander Graf, 2011/06/14
- Re: [Qemu-devel] [PATCH] xen: avoid tracking the region 0xa0000 - 0xbffff, Stefano Stabellini, 2011/06/14
- Re: [Qemu-devel] [PATCH] xen: avoid tracking the region 0xa0000 - 0xbffff, Alexander Graf, 2011/06/14
- Re: [Qemu-devel] [PATCH] xen: avoid tracking the region 0xa0000 - 0xbffff, Alexander Graf, 2011/06/15
- Re: [Qemu-devel] [PATCH] xen: avoid tracking the region 0xa0000 - 0xbffff, Stefano Stabellini, 2011/06/15