Re: Linux Post codes during runtime, possibly OT
H. Peter Anvin (hpa@transmeta.com)
Sat, 27 Jan 2001 12:47:59 -0800
Rogier Wolff wrote:
>
> H. Peter Anvin wrote:
> > Followup to: <3A709E99.25ADE5F6@echostar.com>
> > By author: "Ian S. Nelson" <ian.nelson@echostar.com>
> > In newsgroup: linux.dev.kernel
> > >
> > > I'm curious. Why does Linux make that friendly 98/9a/88 looking
> > > postcode pattern when it's running? DOS and DOS95 don't do that.
> > >
> > > I'm begining to feel like I can tell the system health by observing it,
> > > kind of like "seeing the matrix."
>
> > It output garbage to the 80h port in order to enforce I/O delays.
> > It's one of the safe ports to issue outs to.
>
> Yes, because it is reserved for POST codes. You can get "POST
> debugging cards" that simply have a BIN -> 7segement encoder and two 7
> segment displays on them. They decode 0x80. That's what it's for.
>
Again, if you want to change it, find another safe port, test the hell
out of it, an *PUBLICIZE IT* so noone will use it in the future.
-hpa
--
<hpa@transmeta.com> at work, <hpa@zytor.com> in private!
"Unix gives you enough rope to shoot yourself in the foot."
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