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Re: [Qemu-devel] [PATCH] hw/arm/virt: Allow zero address for PCI IO spac
From: |
Alexander Gordeev |
Subject: |
Re: [Qemu-devel] [PATCH] hw/arm/virt: Allow zero address for PCI IO space |
Date: |
Tue, 13 Oct 2015 13:48:38 +0100 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
On Tue, Oct 13, 2015 at 09:16:34AM +0100, Peter Maydell wrote:
> On 13 October 2015 at 07:31, Alexander Gordeev <address@hidden> wrote:
> > On Mon, Oct 12, 2015 at 10:03:03PM +0100, Peter Maydell wrote:
> >> On 12 October 2015 at 21:55, Alexander Gordeev <address@hidden> wrote:
> >> > Currently PCI IO address 0 is not allowed even though
> >> > the IO space starts from 0. As result, PCI IO is not
> >> > possible to use at all.
> >>
> >> I don't see any reason for us not to allow 0 IO addresses,
> >> but I'm not sure how your your conclusion follows. It
> >> should be entirely possible to map PCI IO to some other
> >> address than zero in the IO window, which is what I would
> >> have expected the guest to do.
> >
> > You are right - my changelog is incorrect. The rest of IO
> > space should be alright.
> >
> > However, as 0 IO address is exposed via "ranges" to the guest,
> > it must be usable - isn't it? So it either should be allowed
> > or the range should be different.
>
> Depends on your point of view. If you take the Linus Torvalds
> view that 0 is always an invalid PCI address, then you'll
> never try to use it anyway.
>
> In any case, setting pci_allow_0_address is the right thing,
> so we can just change the commit message in this patch.
I will post v2 with an updated changelog then.
> Incidentally, why is this a property on the machine
> and not on the PCI controller device?
I am CC-ing Laurent Vivier who introduced the flag.
But IMO it *is* a machine property, not PCI controller's
one, unless I am missing something.
Thanks!
> thanks
> -- PMM
--
Regards,
Alexander Gordeev
address@hidden
- [Qemu-devel] [PATCH] hw/arm/virt: Allow zero address for PCI IO space, Alexander Gordeev, 2015/10/15
- Re: [Qemu-devel] [PATCH] hw/arm/virt: Allow zero address for PCI IO space, Peter Maydell, 2015/10/15
- Re: [Qemu-devel] [PATCH] hw/arm/virt: Allow zero address for PCI IO space, Alexander Gordeev, 2015/10/15
- Re: [Qemu-devel] [PATCH] hw/arm/virt: Allow zero address for PCI IO space, Peter Maydell, 2015/10/13
- Re: [Qemu-devel] [PATCH] hw/arm/virt: Allow zero address for PCI IO space,
Alexander Gordeev <=
- Re: [Qemu-devel] [PATCH] hw/arm/virt: Allow zero address for PCI IO space, Peter Maydell, 2015/10/15
- Re: [Qemu-devel] [PATCH] hw/arm/virt: Allow zero address for PCI IO space, Laurent Vivier, 2015/10/13
- Re: [Qemu-devel] [PATCH] hw/arm/virt: Allow zero address for PCI IO space, Michael S. Tsirkin, 2015/10/13
- Re: [Qemu-devel] [PATCH] hw/arm/virt: Allow zero address for PCI IO space, Peter Maydell, 2015/10/13
- Re: [Qemu-devel] [PATCH] hw/arm/virt: Allow zero address for PCI IO space, Michael S. Tsirkin, 2015/10/13
- Re: [Qemu-devel] [PATCH] hw/arm/virt: Allow zero address for PCI IO space, Peter Maydell, 2015/10/13
- Re: [Qemu-devel] [PATCH] hw/arm/virt: Allow zero address for PCI IO space, Peter Maydell, 2015/10/15
- Re: [Qemu-devel] [PATCH] hw/arm/virt: Allow zero address for PCI IO space, Laurent Vivier, 2015/10/16
- Re: [Qemu-devel] [PATCH] hw/arm/virt: Allow zero address for PCI IO space, Michael S. Tsirkin, 2015/10/16
- Re: [Qemu-devel] [PATCH] hw/arm/virt: Allow zero address for PCI IO space, Peter Maydell, 2015/10/16