Re: [Xen-devel] progress and a problem

[ron minnich <rminnich@xxxxxxxx>]

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.
ron



-------------------------------------------------------
This SF.Net email sponsored by Black Hat Briefings & Training.
Attend Black Hat Briefings & Training, Las Vegas July 24-29 - 
digital self defense, top technical experts, no vendor pitches, 
unmatched networking opportunities. Visit www.blackhat.com
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxxx
https://lists.sourceforge.net/lists/listinfo/xen-devel