Re: [ibm-acpi-devel] [PATCH] Remove 9 second reboot delay on Lenovo T400/T500

[Matthew Garrett <mjg59@srcf.ucam.org>]

On Thu, Jul 15, 2010 at 08:00:23PM -0300, Henrique de Moraes Holschuh wrote:

> Do you want to escalate this to Lenovo?  I need a clear and consise
> description of the problem and the boxes we know to be affected.

Well, right now we're not doing precisely what Windows does. The other 
possibility is that when the keyboard controller write triggers some SMM 
code, it makes an assumption about some piece of hardware state that 
isn't true and loops for a while to see if it changes. If we knew what 
that was then we could ensure that we're performing the same state 
change on our way down to reboot.

One thing that would be worth checking is whether performing the 
keyboard controller writes from userspace with a minimal kernel and 
init=/bin/bash shows the 9-second pause or not - and then, ideally, see 
whether the same is also true under DOS.

-- 
Matthew Garrett | mjg59@srcf.ucam.org