Re: [Xen-devel] kexec: Clear notes during setup

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 04.05.12 at 17:19, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:
> On 04/05/12 13:51, Jan Beulich wrote:
>>>>> On 04.05.12 at 13:42, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:
>>> I know that xen-unstable is on a feature freeze, and this is not
>>> strictly a bugfix (yet; see below), but as it is safe and designed to
>>> help clarity in the case of a crash, so I request that it be considered
>>> for inclusion.
>>>
>>> I have constructed an artificial case where the information reported in
>>> 1 per-cpu crash note was stale by using low_crashinfo mode, crashing
>>> Xen, allowing it to reboot, offlining a CPU then re-crashing Xen.  This
>>> leaves stale register state written into the offlined CPU crash
>>> information.  In this case, the information was stale but correct, due
>>> to the predictable nature of the Xen crash path from the 'C' debug key,
>>> but there is no guarantee that in the case of a real crash, the same
>>> will still be true.
>> Apart from the missing blanks in the for() statement (which could as
>> well be a simple memset() afaict),
>> Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
>>
>> I personally would think that this can go in as a bug fix.
>>
>> Jan
> 
> How would you format the for loop differently? (Not that I mind - just
> so I know for next time)

        for ( i = 0; i < (crash_heap_size >> PAGE_SHIFT); ++i )

> As for clear_page vs memset - clear_page is faster, and liable to be
> conditionally tuned more in the future.

Certainly, but does this matter here?

Jan


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