Re: IO delay, port 0x80, and BIOS POST codes

[Richard B. Johnson]

On Thu, 14 Mar 2002, Martin Wilck wrote:

> 
> Hello,
> 
> the BIOS on our machines (Phoenix) uses IO-port 0x80 for storing
> POST codes, not only during sytem startup, but also for messages
> generated during SMM (system management mode) operation.
> I have been told other BIOSs do the same.
> 
> Unfortunately we can't read this information because Linux uses
> port 80 as "dummy" port for delay operations. (outb_p and friends,
> actually there seem to be a more hard-coded references to port
> 0x80 in the code).
> 
> It seems this problem was always there, just nobody took notice of it yet
> (at least in our company). Sometimes people wondered about the weird POST
> codes displayed in the LCD panel, but who cares once the machine is up...
> 
> Would it be too outrageous to ask that this port number be changed, or
> made configurable?
> 
> Martin

This is a 'N' year-old question. Do you know of a port that is
guaranteed to exist on the Intel/PC/AT class machine? If so, submit
a patch.  I proposed using 0x19h (DMA scratch register) several
years ago, but it was shot down for some reason. Then I proposed
0x42 (PIT Misc register), that too was declared off-limits. So
I suggested that the outb to 0x80 be changed to an inp, saving 
%eax on the stack first. That too was shot down. So, you try
something... and good luck.

Cheers,
Dick Johnson

Penguin : Linux version 2.4.18 on an i686 machine (797.90 BogoMips).

                 Windows-2000/Professional isn't.