SiS630 Software Watchdog Timer

Spirit spirit at
Mon Mar 17 08:09:01 CET 2003

Hello Steve,

Monday, March 17, 2003, 4:56:02 AM, you wrote:

SG> Spirit wrote:
>>   I've been reading the SIS630 datasheet and found out that the
>>   chipset has a watchdog timer (for some reason they call it
>>   'software') similar to that of the i810.
>>   Does anybody here know if there is a ready driver for that thing?

SG> Not aware of a linux driver, but you might want to turn off the software 
SG> watchdog earlier, if you use compression.  Right now it is disabled in 
SG> southbridge.c which is too late since decompression takes a few seconds.

That shouldn't be a problem unless it takes 5 seconds to get to the
southbridge.c code. But of course, moving it to an earlier position is
a good idea.

However, what I was asking for is how to enable and make use of it,
not how to disable it. I think I'll need to look into the i810-tco.c
from the kernel sources and try to modify it for SIS630.

SG> This will do it in
SG> #define ACPI_BASE_ADDR          0x5000

Speaking of ACPI... I can't get it working with LinuxBIOS. ospm_*.o
modules won't load and the kernel complains on being unable to read
ACPI tables.

SG> There are some other simplifications that can be put into
SG> (the gdt reload is not necessary after the Eric's changes in c_start.S), 
SG> but I haven't had time to make a diff and send it to Ron.

What I would really like to see somewhere in the LinuxBIOS code is the
options to disable SiS630 embedded modem and audio controllers. I
browser through the datasheet and didn't find how to disable them. I
probably should re-read it, but if anyone knows the way already, I'd
appreciate showing it to me.

>>  I'm having problems with the serial console when booting LinuxBIOS on
>>  a pcchips m787cl+ motherboard. The serial works for output (I can see
>>  what the box says) but doesn't for input (I can't login from the
>>  serial console). If I boot the same kernel with the same parameters
>>  (console=ttyS0,9600n8) using the original motherboard's BIOS (AMI), I
>>  don't have any problems at all.
>>  Any suggestions?
SG> I assume you changed "option TTYS0_BAUD=38400" in 
SG> /mainboard/pcchips/m787cl+  to 9600?

Yes, I did. But that's not the problem. Or at least not the main one.
It was a problem of an old init, as Ron suggested. I ugraded init and
the problem is gone.

Best regards,
 Spirit                            mailto:spirit at

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