[coreboot] [PATCH] Halt TCO timer on Intel 3100 chipset

joe at smittys.pointclark.net joe at smittys.pointclark.net
Sun Mar 30 16:18:06 CEST 2008

Quoting Ed Swierk <eswierk at arastra.com>:

> On Sat, Mar 29, 2008 at 5:20 PM,  <joe at smittys.pointclark.net> wrote:
>> After thinking about it.....
>> What are the advantages of disabling the TCO timer (besides
>> rebooting)? Doesn't the system need this to run properly? By setting
>> the no reboot the timer is still running....does it need to be?
> The point of the TCO timer is to let a system recover automatically by
> sending an interrupt and then rebooting if the OS crashes. While
> operating systems can crash for all sorts of reasons, coreboot code
> doesn't generally crash unless there's a hardware failure or
> misconfiguration that will not correct itself by rebooting. Thus it
> makes sense to disable the timer in coreboot and let a TCO-aware
> payload re-enable it.
> The TCO timer has no other purpose that I'm aware of, so it doesn't
> matter whether coreboot neuters its effect by setting NO_REBOOT or
> halts it completely by setting TCO_TMR_HALT. Leaving the timer running
> still causes an interrupt to occur on timeout, but I think it's a
> no-op unless the OS is paying attention.
> This document explains the TCO timer in more detail:
> ftp://download.intel.com/design/chipsets/applnots/29227301.pdf.
> --Ed
Thanks for the explanation Ed. That makes perfect sense.

Thanks - Joe

More information about the coreboot mailing list