On Mon, 2014-05-12 at 22:02 +0200, Francois Romieu wrote: > Alex Williamson <alex.williamson@xxxxxxxxxx> : > [...] > > device MSI will be blocked. The Linux driver doesn't make use of this > > window, so apparently it's not required to make use of MSI-X. This > > It does not really use MSI-X (no RSS). Oh right, I looked for code references to the register but didn't notice that Linux configures it for MSI, not MSI-X. In my brief testing I only saw that Windows generates interrupts on the first vector, so perhaps not much lost without the extra vectors. I guess it's this patch that proves that MSI-X can be configured without this backdoor then. Do you have any insight into why this exists? > > quirk makes the device work with the Windows driver that does use this > > window for MSI-X, but I certainly cannot recommend this device for > > assignment (the Windows 7 driver also constantly pokes PCI config > > space). > > Do you have some offsets for those ? I believe it was 0x80, which is 0x10 off from the PCIe capability, so the link control register. I don't seem to have a log, but I'll regenerate one tonight to get the exact sequence (the interface is in use right now). > > diff --git a/hw/misc/vfio.c b/hw/misc/vfio.c > > index 9cf5b84..c3d2f7a 100644 > > --- a/hw/misc/vfio.c > > +++ b/hw/misc/vfio.c > [...] > > + * "address latched" indicator. Bits 12:15 is a mask field, which we're > > + * going to ignore because we don't really know what it means and the MSI-X > > + * area always seems to be accessed with a full mask. > > s/seems to/should always/ > > Double word accesses requires the full mask. The MSIX area should be accessed > through double words. Good to know, I'll amend the comment. Thanks! Alex -- 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
