[PATCH] nvram buffering/error logging port to 2.6

Anton Blanchard anton at samba.org
Tue Dec 2 08:09:40 EST 2003


> This is a port of the nvram buffering/error logging code from 2.4 to
> 2.6.  I should also note that I included moving /proc/rtas to
> /proc/ppc64/rtas.

Taking a step back, why do we need to buffer error log entries in NVRAM?

My thoughts when I added the original event-scan userspace interface were:

1. Machine boots, we execute event-scans but dont request error log
2. When the rtas proc file is opened we then start requesting error log

Is this less reliable? Well we already have a window between where we do
the event scan and when we write the information to NVRAM. Im guessing
writing NVRAM isnt fast, we could easily lose or get corrupted event
scan data if the machine locked up in this window.

NVRAM is a limited resource, how do we avoid overflowing it during boot?
Could we lose error log information if we end up with a bunch of event-scan
error logs?

The real way to fix this window is to have a better interface to the error
log information (ie a read error log RTAS call and a discard error log
RTAS call, you call discard error log once you have successfully
committed the error log to disk).


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