Intel i8xx watchdog driver

[Scott Long]

Doug Ambrisko wrote:
> Scott Long writes:
> | Wm. Daryl Hawkins wrote:
> | > I've written a driver for the Intel i8xx TCO watchdog timer for both 
> | > FreeBSD-CURRENT and FreeBSD-STABLE.  
> |
> | This is wonderful.  I'd be happy to test it and shepherd it in.  Does it
> | support the intel 750x chips also?
> 
> All ICH chips that I've touched support this with the device ID updated
> as needed.  FYI there is a new watchdog device in the 6300ESB.  Not
> sure if it is in prior ICH chips.  It is interesting in that during the
> first expire it will generate and interrupt then it will reboot on the
> next expire.  So if you have an ICH then you can use it.
> 

In reading the code, it appears that it is indeed an ICHx service and
not limited to just i8xx chipsets.  I have a few issues with how the
probe and attach are done, and I'm addressing these in a private mail
right now.  It's funny that I was reading the Intel ICH5 docs last night
and didn't come across this feature at all.

I'm not sure if I like the idea of auto-reboot on second expire, unless
it is configurable (i.e. you can turn that feature off depending on the
situation).  I understand it's purpose though.

> A nice concept would be to have a SW watchdog based on the clock tickle
> the HW watchdog.  If the SW watchdog goes off you get a panic.
> 
> Interesting caveats are having the watchdogs going off while in kgdb/ddb.
> 

Talking with PHK about this now.  There seems to be a growing need for a
mechanism that can inform registered listeners that DDB is about to be
entered.  It's just a random thought in my brain right now, need more
time to flesh it out.

> Caveat to the ICH TCO timer is that if the speaker output out of the ICH 
> has a pull up resistor on it then the TCO reset is disabled and will not
> reset the system.  I ran into this on a motherboard at a prior company.
> You cannot via SW disable this feature :-(
> 
> I have code for the SIS 630 chipset that I can give to anyone interested.

More support it wonderful!  I don't have any hardware to test it on, though.

Scott