[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] Mapping pci resources for graphics passthrough
It¹s that way because a BAR base has to be aligned on a boundary the power-of-two size of the BAR. Passing thru gfx before may not have worked because the PCI I/O hole below 4GB was not big enough. That is fixed now in xen-unstable by dynamically sizing the hole. -- Keir On 22/01/2009 00:29, "Alexia Benington" <alexbenington@xxxxxxxxx> wrote: > I've been trying to understand the pci_setup function in hvmloader.c in Xen > unstable. I'm kinda lost at Line 328. > base = (resource->base + bar_sz - 1) & ~(bar_sz - 1) > > I'd appreciate if someone could explain to me why base is calculated this way. > Specifically, I don't understand the bitwise AND with the one's complements of > "bar_sz-1". > > The reason why I'm doing this is that I'm hoping to modify hvmloader such that > it can map the correct memory for a PCI-e video card. I've been able to > passthrough the video card to a HVM guest. However, the OS (tried Linux, Vista > or XP) is not able to load the driver correctly, although lspci (on Linux) > does show that the video card has been passed through. I suspect it is because > the video RAM and ROM has not been mapped as required, thus the video BIOS > cannot be loaded. I would like to try out with only one guest first, just to > see if it works and leaving out the complexities of multiplexing the graphics > card with several guests. It is also fine if dom0 loses control of the > graphics card. I can use serial. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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