[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] Re: [PATCH V6 17/32] pci: 64bit bar support.
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] Re: [PATCH V6 17/32] pci: 64bit bar support. |
Date: |
Tue, 3 Nov 2009 15:21:00 +0200 |
User-agent: |
Mutt/1.5.19 (2009-01-05) |
On Tue, Nov 03, 2009 at 02:39:06PM +0200, Michael S. Tsirkin wrote:
> On Tue, Nov 03, 2009 at 02:22:07PM +0200, Avi Kivity wrote:
> > On 11/03/2009 01:47 PM, Michael S. Tsirkin wrote:
> >>
> >> If qemu is compiled with target phys address size 32 bit, emulated
> >> devices can not support a 64 bit BAR. Therefore, according to PCI spec,
> >> such devices should declare all BARs as 32 bit.
> >>
> >>
> >
> > What happens if you take a PCI card that supports 64-bit BARs and stick
> > it into a machine that has a 32-bit physical address space?
> > The firmware/OS will configure the BARs to below 4G.
> >
> >> I think you are right that guests on such systems really do not have a
> >> way to address PCI devices if BAR is set beyond 4G. But pci emulation is
> >> better off not relying on this, IMO. Makes sense?
> >>
> >
> > No. Device emulation shouldn't change with the machine type.
>
> I agree. Issue is, we recompile the *devices* as well.
> It's the device emulation that is broken when compiled
> with target phys addr set to 32 bit, because all devices
> take pcibus_t and cast it to target_phys_addr_t
> and then do stuff with it.
>
> So such emulation should not claim to support 64 bit.
>
> Long term, we should fix all devices and *then* they can claim 64 bit
> support always. As a nice side effect, we'll be able to avoid
> rebuilding devices.
BTW, the right way to do this is probably to move mapping device memory
out of devices proper and into pci.
> > --
> > error compiling committee.c: too many arguments to function
- [Qemu-devel] Re: [PATCH V6 17/32] pci: 64bit bar support., Michael S. Tsirkin, 2009/11/01
- [Qemu-devel] Re: [PATCH V6 17/32] pci: 64bit bar support., Isaku Yamahata, 2009/11/02
- [Qemu-devel] Re: [PATCH V6 17/32] pci: 64bit bar support., Michael S. Tsirkin, 2009/11/03
- Re: [Qemu-devel] Re: [PATCH V6 17/32] pci: 64bit bar support., Avi Kivity, 2009/11/03
- Re: [Qemu-devel] Re: [PATCH V6 17/32] pci: 64bit bar support., Michael S. Tsirkin, 2009/11/03
- Re: [Qemu-devel] Re: [PATCH V6 17/32] pci: 64bit bar support.,
Michael S. Tsirkin <=
- Re: [Qemu-devel] Re: [PATCH V6 17/32] pci: 64bit bar support., Isaku Yamahata, 2009/11/03
- Re: [Qemu-devel] Re: [PATCH V6 17/32] pci: 64bit bar support., Michael S. Tsirkin, 2009/11/03
- Re: [Qemu-devel] Re: [PATCH V6 17/32] pci: 64bit bar support., Isaku Yamahata, 2009/11/04
- Re: [Qemu-devel] Re: [PATCH V6 17/32] pci: 64bit bar support., Michael S. Tsirkin, 2009/11/04