Re: [Xen-devel] [PATCH for-4.5 v6 00/16] Xen VMware tools support

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Tue, 2014-09-23 at 13:35 +0100, George Dunlap wrote:
> On Tue, Sep 23, 2014 at 1:30 PM, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:
> > On Mon, 2014-09-22 at 13:19 -0400, Don Slutz wrote:
> >> >> It sounds plausible, for sure.
> >> >>
> >> >> Even so, why can't the result of that #GP be a calldown into qemu for
> >> >> further processing?
> >> >
> >>
> >> This is not simple in that QEMU does not have access to the VCPU
> >> registers.  Unlike a normal
> >> I/O request, vmware_port (aka vmport) both reads and writes VCPU registers.
> >
> > Are you saying that emulating a normal in or out instruction doesn't
> > require accessing vcpu registers? Are you sure? Surely it needs to
> > either read the source or write the destination register somehow.
> 
> At the moment Xen does all of the decoding of instructions; what it
> sends to qemu is just "Read / Write X bytes at address Y" (along with
> data when appropriate).  Qemu doesn't require access to the registers.

I figured that out later and then forgot to delete the paragraph, sorry.

Ian



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