Messages in this thread | | | Date | Thu, 14 Mar 2002 11:18:43 -0700 | From | Thunder from the hill <> | Subject | Re: IO delay, port 0x80, and BIOS POST codes |
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Richard B. Johnson wrote:
> 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. I also remember this been discussed anually. Making it configurable with a warning might be a solution, but that's nothing we could decide. Maybe add a config option? It night be a [DANGEROUS] one, so the guys and gals who might compile are warned of changing this. I think the problem is that on PC arch anything is quite limited.
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