Re: Linux and POST

Tom Dyas (tdyas@romulus.rutgers.edu)
Sat, 7 Feb 1998 13:36:17 -0500 (EST)


On Sat, 7 Feb 1998, Brian Jones wrote:

> I had left a POST board in to use some of the onboard diagnostics,
> and when linux was booting I glanced over at it and saw the display going
> nuts. When the machine was idle it held at 51, and when I flipped between
> virt terms it jumped to 3F and back to 51. Initalizing swap caused it to
> flash between 88 and 5 other codes so fast the LCD couldn't keep up.
> Compiling the kernel caused the same reaction only a bit slower.
>
> Does linux use 80h, as a status display or some form of
> communication channel?

Actually neither. It uses it as an arbirary place to dump random data for
the __SLOW_DOWN_IO macro. See source file linux/include/asm-i386/io.h for
more information.

The inb_p, outb_p macros use it to add a "pause" of sorts.

Tom

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