Re: [Xen-devel] Re: [PATCH] Xen Guest Kexec

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 3 Mar 2006, at 09:14, Keir Fraser wrote:

> Well, the trick I described is good for at least 'non-exceptions' 
> (i.e., it'll disable 'int x' software interrupts). For exceptions, I 
> guess you should simply avoid causing them? :-)
> In fact, why not install a dummy handler for all vectors (0-255). That 
> is, a valid cs:eip that vectors to a small kexec function to print the 
> state you desire? Setting flags==0 will ensure that softints don't 
> work, but you can print out a useful message if you take a fault. You 
> could try and put in a safe-ish place so it continues to work even for 
> the early stages of the new kernel boot.
Actually a clear-trap-table call is quite easy to add: I checked in a 
patch that will clear the entire trap table if you pass a NULL pointer 
to the set_trap_table hypercall. With that patch in place, if you take 
a fault you will get a register dump in Xen as desired.
Changeset 9109:29f8c87...

 -- Keir


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