Re: setup.S: A20 enable sequence (once again)

From: H. Peter Anvin (hpa@zytor.com)
Date: Mon Nov 06 2000 - 14:56:04 EST


Followup to: <00110618083400.11022@rob>
By author: Robert Kaiser <rob@sysgo.de>
In newsgroup: linux.dev.kernel
>
> The attached patch fixes this by doing "fast A20" enable first and then
> checking if A20 already is enabled. If it is, the keyboard controller sequence
> is skipped. This works for me, so, could people please have a look at this.
>

I just looked at the code, and it's worse than I first thought: if
memory location 0x200 happens to contain 0x0001 when the kernel is
entered, this code with loop indefinitely.

        -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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