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Re: [Xen-devel] unstable changeset 16667 introduced regression


  • To: Bruce Rogers <BROGERS@xxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
  • From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
  • Date: Tue, 15 Jan 2008 08:21:41 +0000
  • Delivery-date: Tue, 15 Jan 2008 00:22:04 -0800
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>
  • Thread-index: AchXT6fX5k5vSsNCEdyI+gAWy6hiGQ==
  • Thread-topic: [Xen-devel] unstable changeset 16667 introduced regression

Can you explain the scenario in more detail? Do you mean the EIP has not
been incremented past the 0xcc opcode? I think the change from
set_system_gate() to set_intr_gate() in that patch is very dubious, now I
take another look at it. I should probably at least revert that, as it's
probably causing guest INT3s to be delivered to Xen as GPFs, with no
corresponding increment of EIP.

I can't see how any other change in the patch would affect guest execution
when gdbstub is not involved as almost all other changes are to gdbstub
code. And probably you are not building Xen with crash_debug=y?

 -- Keir

On 14/1/08 22:57, "Bruce Rogers" <BROGERS@xxxxxxxxxx> wrote:

> Keir,
> I've narrowed down a problem we are now seeing with Virtualized NetWare when
> run on current unstable.
> It started occurring with changeset 16667, which dealt with debugger changes.
> When encountering the INT 3 instruction (opcode 0xcc), the EIP value provided
> in the exception frame is supposed to be at the next instruction following the
> INT 3 instruction.  With this patch included, the EIP value ends up being one
> byte further into the instruction stream.
> 
> I haven't seen where in this patch the problem is coming from, but will keep
> looking.
> 
> - Bruce
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel



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