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SubjectRe: [PATCH] x86: provide a DMI based port 0x80 I/O delay override
Date
Ingo Molnar <mingo@elte.hu> wrote:

> do you have any memories about the outb_p() use of misc_32.c:
>
> pos = (x + cols * y) * 2; /* Update cursor position */
> outb_p(14, vidport);
> outb_p(0xff & (pos >> 9), vidport+1);
> outb_p(15, vidport);
> outb_p(0xff & (pos >> 1), vidport+1);
>
> was this ever needed? This is so early in the bootup that can we cannot
> do any sensible delay. Perhaps we could try a natural delay sequence via
> inb from 0x3cc:
>
> outb(14, vidport);
> inb(0x3cc); /* delay */
> outb(0xff & (pos >> 9), vidport+1);

I've never seen code which would do that, and it was not suggested by any
tutorial I ever saw. I'd expect any machine to break on all kinds of software
if it required this. The only thing I remember being warned about is writing
the index and the data register at the same time using outw, because that
would write both registers at the same time on 16-bit-cards.


BTW: The error function in linux-2.6.23/arch/i386/boot/compressed/misc.c
uses while(1) without cpu_relax() in order to halt the machine. Is this fixed?
Should it be fixed?


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