On 2020/06/29 3:23, Simon Arlott wrote:

On 19/06/2020 00:31, Damien Le Moal wrote:

quoted

On 2020/06/18 21:26, Simon Arlott wrote:

quoted

I haven't verified it, but the BIOS leaves the power off for several
seconds which should be long enough for the HDDs to spin down.

I'm less concerned about those suddenly losing power but it would be
nice to have a stop command sent to them too.

OK. So maybe the patch should be as simple as changing SYSTEM_RESTART state to
SYSTEM_POWER_OFF if reboot=p is set, no ? Since that is consistent with the fact
that reboot=p will cause power to go off, exactly the same as a regular
shutdown, it seems cleaner and safer to use SYSTEM_POWER_OFF for the entire
system, not just scsi disks.

That could be a bit misleading because the power isn't going to stay
off. Some of the network drivers have specific WOL behaviour changes
for a power off.

The point is that the power goes off, same as for a SYSTEM_POWER_OFF shutdown.
It do not think it matters how long it will be off before your BIOS restarts the
laptop power. And actually enabling the NICs WOL function would I think actually
be a very good thing: if the PSU power cycling fails, the machine can still be
remotely woken-up as configured by the user.

Power cycling the PSU is not something that every BIOS will do, so it's
not that simple. It could be a module parameter but I'd be concerned
that some other code will assuming the system should be powered off and
all of my reboots will become power off events.

Or define a SYSTEM_RESTART_P that essentially does what SYSTEM_POWER_OFF does +
the addition of telling the BIOS to restart the PSU, if the machines supports
it. What happens if one does a reboot=p on a machine that does not support it ?
Does this become a shutdown, or does it become a normal reset ?


-- 
Damien Le Moal
Western Digital Research