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Re: [Xen-devel] progress and a problem

On Sat, 26 Jun 2004, Keir Fraser wrote:

> Which stack are you talking about here? When Xen first deschedules
> your while(1), the CPU should write CS,EIP,EFLAGS,SS,ESP onto Xen's
> ring-0 stack.

ok, what interrupt does this? 

> When you get a callback, Xen should see that it is 'interrupting' an
> existing ring-1 activation, and read the appropriate SS,ESP from its
> own (ring-0) stack. When it writes the activation frame for teh
> callback, it will only write CS,EIP,EFLAGS. SS,ESP will not be written
> to your ring-1 stack because the IRET at the end of your callback
> handler will not be changing privilege levels.

ok, I see your point. I'm really puzzled about this bad ss/sp pair. It 
makes no sense.

> Task segments aren't virtualised, so there is no equivalent of
> LTR. The quivalent of LIDT is set_trap_table() which you must have
> called to be taking page faults.

good, that's what I was hoping to hear you say.

I'll keep looking, this is really odd.

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