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Re: [Xen-devel] [PATCH 2/2] xen/conring: Write to console ring even if console lock is busted.


  • To: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Xen-devel <xen-devel@xxxxxxxxxxxxx>
  • From: Keir Fraser <keir.xen@xxxxxxxxx>
  • Date: Tue, 06 Aug 2013 15:44:07 +0100
  • Cc: Tim Deegan <tim@xxxxxxx>, Jan Beulich <jbeulich@xxxxxxxx>
  • Delivery-date: Tue, 06 Aug 2013 14:44:34 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xen.org>
  • Thread-index: Ac6Ss2dJCNkJmx4CZkKUsrMHx4GALw==
  • Thread-topic: [PATCH 2/2] xen/conring: Write to console ring even if console lock is busted.

On 31/07/2013 15:22, "Andrew Cooper" <andrew.cooper3@xxxxxxxxxx> wrote:

> console_lock_busted gets set when an NMI/MCE/Double Fault handler decides to
> bring Xen down in an emergency.  conring_puts() cannot block and does
> not have problematic interactions with the console_lock.
> 
> Therefore, choosing to not put the string into the console ring simply means
> that the kexec environment cant find any panic() message caused by an IST
> interrupt, which is unhelpful for debugging purposes.
> 
> In the case that two pcpus fight with console_force_unlock(), having slightly
> garbled strings in the console ring is far more useful than having nothing at
> all.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> CC: Keir Fraser <keir@xxxxxxx>
> CC: Jan Beulich <jbeulich@xxxxxxxx>
> CC: Tim Deegan <tim@xxxxxxx>

Acked-by: Keir Fraser <keir@xxxxxxx>



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