ThinkPad: reboots after successful shutdown -p

[Xin Li]

On 11/17/19 23:14, Xin Li wrote:
> Hi,
> 
> I recently noticed that if I do a 'shutdown -p' from -CURRENT, the
> system would shut down and seemingly powered off, then it would restart
> after about 5-10 seconds.
> 
> Is this a known issue?  Arguably this is not necessarily a FreeBSD
> issue, but it seems that the Windows 10 installation doesn't have the
> problem, so I guess there might be some difference between our and
> Windows's shutdown sequence.

I've found a workaround for this, for the record, setting
hw.efi.poweroff=0 would make the laptop to correctly shutdown.

However I don't see anything wrong with sys/dev/efidev/efirt.c's
implementation of EFI shutdown; it appears to be essentially the same as
implemented in command_poweroff() in stand/efi/loader/main.c, but
'poweroff' would work just fine in loader.efi.

Can someone familiar with the code shed me some light here? :-)

It looks like what Linux did was to prefer ACPI S5, unless it's not
available or the system have HW_REDUCED flag in FADT, so if we do
something similar it would fix the issue for me, but according to
bugs.freebsd.org/233998 that's not the case for at least Conor's system
(_S5 appears to be in the ACPI dump), so I think it's something else...

Cheers,