Hard drive power saving
mjg59 at srcf.ucam.org
Thu Feb 16 00:39:46 GMT 2006
Having thought about this for a bit, and having come up with a (just
about) plausible explanation for the problem, I've reenabled hard drive
power management in the AC mode change script.
The problem was hangs associated with switching from AC to battery, or
vice-versa. I /think/ the cause for this may have been down to the
laptop hardware sending IDE commands on power change (such as to slow
down CD drive speed), and sending the APM command at the same time may
have then hung the IDE bus. To get around this, I've delayed the sending
of commands until a while after the state change.
It's possible that this isn't the problem, and if so it's likely that
it'll suddenly reappear and start biting people. So, it would be helpful
if you could let me know if changing your power source suddenly results
in the machine hanging (either at the time of the event, or the next
time it tries any disk access).
Matthew Garrett | mjg59 at srcf.ucam.org
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