On Sat, 2007-09-15 at 12:38 +0300, Avi Kivity wrote: > I don't see why there is a difference. With mmio, the host tells the > guest where the ring is. With dma, the guest tells the host where the > ring is. In both cases, you need some form of communication (read-only > for mmio, write-only for dma). > > For mmio, the mechanism is standardized within pci; for dma it is not, > but it is still just as simple, write to some word in pci config space > and you're done.
No, you already need a r/o, whatever you use. That's because you need to describe the features of the device (eg disk size). > If early printk can't handle pci, we can provide a pio port that does > byte-at-a-time output. It's not that it can't handle PCI, it's that it now needs to find a page to use. That's less trivial than using an already-existing page. As for making suspend/resume more complex, I can't see it. Make the guest memory a few pages bigger, and don't tell the guest about those extra pages (that's waht lguest does today: those mmio pages are just above top of "normal" RAM). Now, we might want some mmio space for our "kick", rather than a hypercall, but that's separate from the ring buffers. Rusty. ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
