> What about 64-bit systems that use an IOMMU? Don't they already have a
> 64-bit physical -> 32-bit IO address space mapping? I don't know if this
> mapping is per-bus or system global.
If it's an Intel x86_64 machine (no IOMMU yet), IIRC the 32-bit PCI devices
are capable of DMA-ing into the bo
> > IIUC PCI cards don't really have "DMA engines" as such. The PCI bridge
> > just maps PCI address space onto physical memory. A Busmaster PCI device
> > can then make arbitrary acceses whenever it wants. I expect the default
> > mapping is a 1:1 mapping of the first 4G of physical ram.
>
> I was
> > Could maybe have the (inevitable) kernel portion of the code grab the
> > interrupt, and not ack it until userspace does an ioctl on a special file
> > (or something like that?). There are patches floating around for
> > userspace IRQ handling, so I guess that could work.
>
> This still requir
On Thu, Jan 05, 2006 at 06:10:54PM +, Paul Brook wrote:
> On Thursday 05 January 2006 17:40, Mark Williamson wrote:
> > > - IRQ sharing. Sharing host IRQs between native and virtualized devices
> > > is hard because the host needs to ack the interrupt in the IRQ handler,
> > > but doesn't reall
On Thursday 05 January 2006 17:40, Mark Williamson wrote:
> > - IRQ sharing. Sharing host IRQs between native and virtualized devices
> > is hard because the host needs to ack the interrupt in the IRQ handler,
> > but doesn't really know how to do that until after it's run the guest to
> > see what
> - IRQ sharing. Sharing host IRQs between native and virtualized devices is
> hard because the host needs to ack the interrupt in the IRQ handler, but
> doesn't really know how to do that until after it's run the guest to see
> what that does.
Could maybe have the (inevitable) kernel portion of t
> I'm wondering if it would be possible to modify QEMU such that VMs could
> access PCI devices on the host system. And, if it would be possible at
> all, how much work this would be.
Sounds doable but would require a fair bit of hacking - I think the idea of
doing this under QEmu came up once be
> Background: I'm one of the developers of MadWifi, which is a linux
> driver for WLAN cards based on Atheros chipsets. QEMU could be a great
> help in testing distribution-specific issues, as well as issues related
> to SMP operation. The only downside is that it's not easily possible to
> emulate
Hi all.
Disclaimer: I'm quite new to things like virtual machines, and even
half-baked when it comes to QEMU. I'm aware that my idea might be
absurd, but still it's worth a try :)
I'm wondering if it would be possible to modify QEMU such that VMs could
access PCI devices on the host system. And,
