New patch was Re: follow-up to guest debug support patches

[Kip Macy <kip.macy@gmail.com>]

Updated single patch for inspection is at:

http://www.fsmware.com/xenofreebsd/gdb/050312/patch

> patch1:
> It seems to be missing a way to undo the foreign mappings on exit?
No change.

> 
> The memcpy copying the user_ctxt is now after if gets used (addtl.
> VMX checks)  Looks like he wasn't too careful when forward
> porting -- scary :-(  Maybe the VMX check should just look at the
> context passed in.

Fixed. FYI the callers don't correctly handle the EINVAL returned there.

 > Not sure why he's skipping setting DONEFPUINIT, kernel mode and clearing
> IOPL bits though.
Fixed.
 
> Doesn't the change in traps.c break in-guest debugger support?  It seems
> to always pause the domain if it is in kernel, an in-guest debugger
> which has set a breakpoint in the kernel will never get the int3.  I
> think
> this needs some kind of flag to enable/disable this behaviour.

Long term this will be a guest boot-time / run-time settable option.
Right now, for the sake of expediency, it is xen compile-time option -
see Rules.mk.

> I think the order in arch_final_setup_guest should be:
> 
> - check cs/ss in passed in cpu_ctxt (before doing anything)
> - update DONEFPUINIT and TF_kernel_mode flags
> - copy user_ctxt
> - copy fpu ctxt
> - clear iopl
> - exit if updating (EDF_DONEINIT)

Fixed.

Let me know if there is anything else I missed. Thanks.


                -Kip


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