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Re: [Qemu-devel] [PATCH 2/3] Add a new PCI region type to supports 64 bi
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [PATCH 2/3] Add a new PCI region type to supports 64 bit ranges |
Date: |
Thu, 29 Dec 2011 18:16:59 +0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Thu, Dec 29, 2011 at 06:32:37PM +1300, Alexey Korolev wrote:
>
> >>@@ -69,6 +72,8 @@ static enum pci_region_type pci_addr_to_type(u32 addr)
> >> {
> >> if (addr& PCI_BASE_ADDRESS_SPACE_IO)
> >> return PCI_REGION_TYPE_IO;
> >>+ if (addr& PCI_BASE_ADDRESS_MEM_TYPE_64)
> >>+ return PCI_REGION_TYPE_PREFMEM_64;
> >This seems dangerous - a 64bit bar can be non-prefetchable - getting
> >this wrong could cause random (hard to debug) crashes.
> >
> Just out of curiosity - how this could happen? Having 64bit
> non-prefetchable BAR implies that the device is not behind
> any bridge (as bridges describe 64bit ranges for prefetchable
> memory only). Is it possible on nowadays systems?
Yes. qemu puts all devices directly on the root bus.
system devices are also commonly located on the root bus.
- [Qemu-devel] [Seabios] [PATCH 0/3] 64bit PCI BARs allocations, Alexey Korolev, 2011/12/27
- [Qemu-devel] [PATCH 3/3] Changes related to secondary buses and 64bit regions, Alexey Korolev, 2011/12/28
- Re: [Qemu-devel] [PATCH 3/3] Changes related to secondary buses and 64bit regions, Alexey Korolev, 2011/12/29
- Re: [Qemu-devel] [PATCH 3/3] Changes related to secondary buses and 64bit regions, Michael S. Tsirkin, 2011/12/29
- Re: [Qemu-devel] [PATCH 3/3] Changes related to secondary buses and 64bit regions, Michael S. Tsirkin, 2011/12/29
- Re: [Qemu-devel] [PATCH 3/3] Changes related to secondary buses and 64bit regions, Alexey Korolev, 2011/12/30