hack for getting suspend/resume to half work on an IBM Thinkpad x60s [SMP]

[Andrea Bittau]

On Mon, Oct 02, 2006 at 02:24:18PM -0400, John Baldwin wrote:
> well as resuming the local APIC.  Can you test this w/o SMP and make sure it 
> works?

I'll give it a shot as soon as I get some time.

> Probably we need to get onto the BSP via sched_bind() during suspend and then 
> stop the other CPUs using stop_cpus().  The hard part, however, is properly 

Yea I do that in acpi_SetSleepState().  Essentially I copied the shutdown code.

> resuming the darn things.  Do you know what mode the CPUs come back up in?  
> It looks like we need to resend startup IPIs to them from your patch.

Yea it all comes back in real mode.  I've tried using the standard freebsd "boot
code" for waking up the second CPU.  There were some issues with the BSP not
using PTD_Idle.  I don't know enough about computers and freebsd to know what
exactly that means.  Also, when the second CPU came back, if it entered the
scheduler, it would die, so I had to leave it in the idle loop by setting the
cpu_hlt mask.

Anyway, the correct way to do it I think is to generalize the save state &
wakeup code used by the BSP in acpi_sleep_machdep().  That is, the second core
should save its state and wake up the same way as the BSP does.  It should not
use the "come to life mechanism" used at boot-time.  The reason is that the
memory is setup properly and the second core should have saved registers which
make sense so less "initialization and setup" needs to be performed.