Re: Status of ioemu code in unstable?

[Arun Sharma <arun.sharma@intel.com>]

John Byrne wrote:
> 
> Hi,
> 
> I've been trying to find out from the xen-devel archives and Google and 
> I cannot seem to find the information I'm looking for.
> 
> I assume the goal of the ioemu is to provide necessary support for 
> non-paravirtualized guess running on VT-x hardware. At a minimum I'd 
> guess you'd need BIOS emulation, display card emulation, and timer/ 
> interrupt emulation.

See foil 10 of:

http://summit.xensource.com/pdfs/Xen_VT_Status_TODO_Intel_ASharma_EtAl.pdf

for a summary of what's working.

Since then, we've added support for BIOS emulation (tools/firmware).
The current device models are based on qemu-0.6.1.

> I'd like to know what's there; what works; and what else might be 
> needed. A pointer to the information or a summary would be appreciated. 
> Also, there is one item in the todo list in the wiki that suggests that 
> the ioemu code will all be re-written. Is this for performance reasons?

Yes, switching to dom0 for every I/O request is very expensive. But that 
was the easiest and cleanest initial implementation.

We've also accelerated the PIT by moving it into the hypervisor and have 
patches for implementing the local APIC support in xen.

	-Arun