[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-ia64-devel] iosapic virtualisation
On Wed, 2006-02-01 at 10:11 +0100, Tristan Gingold wrote: > Le Mardi 31 Janvier 2006 20:53, Alex Williamson a écrit : > > * Assigning vectors as defined by the domain; I think this is > > covered by some of the comments included about future problems, > > but maybe we should address this one now. We should probably > > start out with separate vector spaces between xen and each > > domain and keep a mapping table between xen vectors (ie. what's > > actually programmed into the IOSAPIC RTE) and what the domains > > tried to program via iosapic_guest_write(). It's probably > > reasonable to assign xen vectors from highest to lowest such > > that xen will end up with the highest priority external > > interrupts, dom0 the next highest, and so on. > I don't really understand your point here. > With the patch there is no relations between IOSAPIC vector and domain > vector. > That's the reason why there is an heavy weight look-up. If we create a > look-up table (see previous point), we do what you describe here, don't we ? Ah, I see it now. I missed how we're ignoring the vector from the domain when we call iosapic_register_intr() then we store it in rte->vec for the call back to the domain. Perfect. > > * We need to paravirtualize reads of the IOSAPIC as well as > > writes. Since the IOSAPICs use a windowing register scheme, a > > domain reading an IOSAPIC could interfere with Xen writing or > > cause races with other domains. This will also enable us to > > hide the physical IOSAPIC structure if we need to at some point. > Ok. I think this point is rather moot because linux doesn't read IOSAPIC > (except version, which is not windowed). However for completion I will do > it. Doesn't iosapic_version() call iosapic_read() which writes to the IOSAPIC_REG_SELECT register? I was concerned that's where we'd run into a problem, but maybe I'm forgetting something about how IOSAPICs work. By the way, I don't see iosapic.h in the patch set, probably why it didn't compile for me. Thanks, Alex -- Alex Williamson HP Linux & Open Source Lab _______________________________________________ Xen-ia64-devel mailing list Xen-ia64-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-ia64-devel
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