Re: Preserving CMC/CPE records across reboot

[Keith Owens <kaos@sgi.com>]

Alex Williamson (on Fri, 13 Jan 2006 08:05:07 -0700) wrote:
>On Fri, 2006-01-13 at 11:46 +1100, Keith Owens wrote:
>> 
>> We should be able to keep the first few CMC/CPE records for each cpu in
>> NVRAM and discard the later ones if we start getting a backlog.  Then
>> if the system hangs while processing a CMC/CPE, the data will still be
>> available in NVRAM and will be processed on the next boot.  If the
>> reboot hangs again in salinfo processing then we have a solid error,
>> either cpu or SAL, so switch the offending cpu out of the system.
>> 
>> Any objections from other platforms?
>
>   Sorry, it's been a while since I've looked at this code, but how do
>we determine how many records can be stored in NVRAM?  I would guess
>that for CPEs at least, it's platform dependent.  If it can be done w/o
>losing records, it's probably ok, but I'm not sure I understand the
>details.  Thanks,

By counting the number of interrupts and subtracting the number of
'clear' events issued by user space.  It would be messy but possible.

Jack Steiner has pointed out that the SGI prom never saves CMC/CPE
records anyway, which means that my idea would not solve the problem of
records being lost due to reboot.  So I am dropping this idea.