On Wed, Jul 28, 2010 at 04:13:19PM -0600, Alex Williamson wrote: > On Thu, 2010-07-29 at 00:57 +0300, Michael S. Tsirkin wrote: > > On Wed, Jul 28, 2010 at 03:57:02PM -0600, Alex Williamson wrote: > > > > > > Something like GET_MSIX_VECTORS seems like a user library routine to me. > > > The PCI config space is well specified and if we try to do more than > > > shortcut trivial operations (like getting the BAR length), we risk > > > losing functionality. And for my purposes, translating to and from a > > > made up API to PCI for the guest seems like a pain. > > > > Won't a userspace library do just as well for you? > > You mean aside from qemu's reluctance to add dependencies for more > libraries? Main reason is portability. So as long as it's kvm-only stuff, they likely won't care. > My only concern is that I want enough virtualized/raw config > space that I'm not always translating PCI config accesses from the guest > into some userspace API. If it makes sense to do this for things like > MSI, since I need someone to figure out what resources can actually be > allocated on the host, then maybe the library makes sense for that. > Then again, if every user needs to do this, let the vfio kernel driver > check what it can get and virtualize the available MSIs in exposed > config space, and my driver would be even happier. > > Alex It would? guest driver might or might not work if you reduce the number of vectors for device. So I think you need an API to find out whether all vectors can be allocated. And these are examples of why virtualizing is wrong: 1. hides real hardware 2. no way to report errors -- MST -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
