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SubjectRe: [Xen-devel] Re: [RFC, PATCH 0/24] VMI i386 Linux virtualization interface proposal
Zachary Amsden wrote:
> Chuck Ebbert wrote:
>> In-Reply-To: <>
>> On Wed, 15 Mar 2006 10:25:22 +0000, Christoph Hellwig wrote:
>> I'd like to see a test harness implementation that has no actual
>> hypervisor functionality and just implements the VMI calls natively.
>> This could be used to test the interface and would provide a nice
>> starting point for those who want to write a VMI hypervisor.
> I was going to make one yesterday. But Fry's electronics stopped
> carrying flashable blank PCI cards. :) Anyone know of a vendor?
It's very practical to just patch Qemu to load a VMI rom as an option
ROM. That makes such an example VMI ROM very practical without having
to build a special PCI device.


Anthony Liguori
> It is possible to do in a software layer, although it really is a lot
> easier to have the BIOS take care of all the fuss of finding a place
> in low memory for you to live, setting up the various memory maps and
> everything else for you.
> There is enormous benefit to having such a layer - you have a very
> power test harness, not just to make sure VMI works, but even more
> importantly, to inspect and verify the native kernel operation as
> well. You have a plethora of imporant hooks into the system, which
> feed you knowledge you can not otherwise gain about which page tables
> have been made active, when you take IRQs, where the kernel stack lives.
> All of this is ripe for a debug harness that can verify the kernel
> doesn't overflow the kernel stack, doesn't write to active page table
> entries without proper accessors and subsequent invalidations, and
> obeys the rules that are required for correctness when running under a
> hypervisor. You probably even want to do hypervisor like things -
> such as write protecting the kernel page tables so that you can be
> confident there are no stray raw PTE accesses.
> We actually found one (harmless on native) in i386, which was enabling
> NX bit.
> Zach
> _______________________________________________
> Xen-devel mailing list

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