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Re: [Qemu-devel] Using PCI config space to indicate config location
From: |
Rusty Russell |
Subject: |
Re: [Qemu-devel] Using PCI config space to indicate config location |
Date: |
Thu, 11 Oct 2012 11:13:25 +1030 |
User-agent: |
Notmuch/0.13.2 (http://notmuchmail.org) Emacs/23.3.1 (i686-pc-linux-gnu) |
"Michael S. Tsirkin" <address@hidden> writes:
> On Wed, Oct 10, 2012 at 08:36:12AM -0500, Anthony Liguori wrote:
>> Rusty Russell <address@hidden> writes:
>>
>> > Gerd Hoffmann <address@hidden> writes:
>> >> So how about this:
>> >>
>> >> (1) Add a vendor specific pci capability for new-style virtio.
>> >> Specifies the pci bar used for new-style virtio registers.
>> >> Guests can use it to figure whenever new-style virtio is
>> >> supported and to map the correct bar (which will probably
>> >> be bar 1 in most cases).
>> >
>> > This was closer to the original proposal[1], which I really liked (you
>> > can layout bars however you want). Anthony thought that vendor
>> > capabilities were a PCI-e feature, but it seems they're blessed in PCI
>> > 2.3.
>>
>> 2.3 was standardized in 2002. Are we confident that vendor extensions
>> play nice with pre-2.3 OSes like Win2k, WinXP, etc?
2.2 (1998) had the capability IDs linked list, indicated by bit 4 in the
status register, but reserved ids 7 and above. ID 9 (vendor specific)
was added in 2.3; it should be ignored, but will require testing of
course, like any change.
2.1 didn't have the capability ID linked list at all; bit 4 in the
status register was reserved.
QEMU's pci.c has capability support, and sets the capabiliy status bit
and list pointer when the driver requests (eg. the eepro100).
> Pre 2.3 it was the case that *all* space outside
> the capability linked list, and any capability not
> recognized by space, was considered vendor specific.
> So there's no problem really.
Oh in theory, sure. In practice, almost certainly. But this needs to
be proved with actual testing.
Cheers,
Rusty.
- Re: [Qemu-devel] Using PCI config space to indicate config location, (continued)
- Re: [Qemu-devel] Using PCI config space to indicate config location, Gerd Hoffmann, 2012/10/09
- Re: [Qemu-devel] Using PCI config space to indicate config location, Anthony Liguori, 2012/10/09
- Re: [Qemu-devel] Using PCI config space to indicate config location, Gerd Hoffmann, 2012/10/09
- Re: [Qemu-devel] Using PCI config space to indicate config location, Rusty Russell, 2012/10/10
- Re: [Qemu-devel] Using PCI config space to indicate config location, Anthony Liguori, 2012/10/10
- Re: [Qemu-devel] Using PCI config space to indicate config location, Michael S. Tsirkin, 2012/10/10
- Re: [Qemu-devel] Using PCI config space to indicate config location,
Rusty Russell <=
- Re: [Qemu-devel] Using PCI config space to indicate config location, Michael S. Tsirkin, 2012/10/10
Re: [Qemu-devel] Using PCI config space to indicate config location, Michael S. Tsirkin, 2012/10/10
- Re: [Qemu-devel] Using PCI config space to indicate config location, Rusty Russell, 2012/10/10
- Re: [Qemu-devel] Using PCI config space to indicate config location, Michael S. Tsirkin, 2012/10/11
- Re: [Qemu-devel] Using PCI config space to indicate config location, Rusty Russell, 2012/10/11
- Re: [Qemu-devel] Using PCI config space to indicate config location, Michael S. Tsirkin, 2012/10/12
- Re: [Qemu-devel] Using PCI config space to indicate config location, Rusty Russell, 2012/10/12
- Re: [Qemu-devel] Using PCI config space to indicate config location, Michael S. Tsirkin, 2012/10/12
- Re: [Qemu-devel] Using PCI config space to indicate config location, Rusty Russell, 2012/10/16
- Re: [Qemu-devel] Using PCI config space to indicate config location, Michael S. Tsirkin, 2012/10/16