Messages in this thread | | | Subject | Re: AMD SC410 boot problems with recent kernels | Date | Sun, 23 Dec 2001 14:16:58 +0100 (CET) | From | (Christer Weinigel) |
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hpa wrote: >> If the board is really _broken_ I have no problem with the fact that in >> the future the manufacturer has either to supply a correct BIOS or a >> workaround patch has to be used. If it's only uggly that there's no BIOS >> routine it would IMHO be better to find a way to make it work again. There >> are fixes for other uggly architectures in the code as well, see the >> Toshiba Laptop reference. If the board may be PC compatible, Linux should >> IMHO boot without further changes.
It is an embedded board with a _mostly_ PC compatible CPU, but it has a few strange bugs/features that have to be worked around. For example look a the fix for the timer and serial port in:
http://www.uwsg.iu.edu/hypermail/linux/kernel/0004.2/0667.html
Especially the serial fix is (IMHO) too ugly to live in the standard kernel.
I'd also suggest that you change the whole gate A20-mess to:
inb $0xee, %al
this will enable A20 propagation on the SC410 and always works, the disadvantage is that it won't work on a normal PC anymore.
>The weird part about your board is that the code clearly *works*, or >your kernel wouldn't boot at all. It somehow poisons the system, >though, and that's utterly bizarre. > >I don't think this is debuggable without access to hardware (and maybe >not even then.)
It has been a few years since I was working on an Elan SC400 board, but if I remember correctly, the Elan CPU has some configuration registers located at some I/O ports that on a normal PC are either "safe" or used for something else.
Additionally, since there normally isn't a keyboard controller on the SC410, accesss to port 0x60 and 0x64 trap into SMI mode, doing I/O to those ports could mess up a badly written BIOS.
My belief is that the SC410 based boards are so strange that one has to have a custom kernel anyways, so asking why it isn't 100% PC compatible and trying to fix that is rather pointless.
/Christer
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