[Savage40] s3switch does segmentation fault / xv overlay on tv weired

[Tim Roberts]

Harald Strack wrote:

>
> I am now since 2 days on googeling and it seems that no one else has 
> the same problems like
> me, so I ask...
>
> System:
> IBM ThinkPad T23 (2647-4MG)
> S3 Inc. SuperSavage IX/C SDR
>
> Debian sarge
> Kernel: 2.6.8, 2.6.11, 2.4.27
> XFree86 Version 4.3.0.1 (Debian 4.3.0.dfsg.1-12.0.1)
> s3switch / Savage driver version: ?? (debian sarge, binary)
>  
> Problem1: s3switch does segmentation fault
>
> s3switch claims:
>
> Devices attached:  CRT LCD TV
> Devices active:    CRT LCD
> Current TV format is NTSC-J


The SuperSavage BIOSes do not maintain the register s3switch uses to 
detect the TV format.  That value is unreliable, as you see.

> $ s3switch pal
> Segmentation fault


Are you comfortable using gdb?  The typical problem here is that the 
BIOS author has left in some debug code that writes progress values to 
an I/O port that they monitor on a logic analyzer.  s3switch only asks 
for permission to write to the VGA I/O ports, so any unexpected write 
causes a Segmentation fault.  If you can catch the problem with gdb and 
get a register dump, you can make sure the failing instruction is an I/O 
port write, get the I/O port number either from the second byte of the 
instruction or the $dx register, and add that port number to the list of 
ioperm calls in the s3switch.c source code.

-- 
Tim Roberts, timr at probo.com
Providenza & Boekelheide, Inc.