Messages in this thread | | | Date | Fri, 20 Oct 2006 10:35:41 -0500 | From | Anthony Liguori <> | Subject | Re: [PATCH 1/7] KVM: userspace interface |
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Avi Kivity wrote: > Anthony Liguori wrote: >>> >>> writel(dst_x_reg, x); >>> writel(dst_y_reg, y) >>> writel(width_reg, w); >>> writel(height_reg, h); >>> writel(blt_cmd_reg, fill); >>> >>> then kvm would cache the first four in a mmap()able memory area and >>> only exit to userspace on the fifth. Userspace would then read the >>> cached registers from memory and emulate the command. >> >> Letting QEMU do a certain amount of emulation after every transition >> would the problem in a more elegant and generic way. >> > > But what amount? A basic block, or several? > > Emulation has its costs. You need to marshal the registers to and > fro. You need to reset qemu's cached translations. You need to throw > away shadow page tables and qemu's softmmu. You increase the time > spent in single threaded code.
Admittedly still a research topic. If you're interested in what we're doing in Xen, check out:
http://xenbits.xensource.com/ext/xen-unstable-hvm.hg (sorry, xenbits is down right now but hopefully it will be fixed quickly).
Regards,
Anthony Liguori
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