cvs commit: src/sys/boot/i386/cdboot cdboot.s

John Baldwin jhb at
Tue Apr 11 12:18:23 UTC 2006

On Tuesday 11 April 2006 12:39 am, Maxim Sobolev wrote:
> sobomax     2006-04-11 04:39:29 UTC
>   FreeBSD src repository
>   Modified files:
>     sys/boot/i386/cdboot cdboot.s
>   Log:
>   When enabling A20 put upper limit on amount of time we wait for the
> keyboard controller to get ready (65K x ISA access time, visually around 1
> second). If we have wait more than that amount it's likely that the
> hardware is a legacy-free one and simply doesn't have keyboard controller
> and doesn't require enabling A20 at all.
>   This makes cdboot working for MacBook Pro with Boot Camp.

You'll probably need to do the same for boot1 and I think BTX.
Alternatively, you should see how the loader is handling A20 and
do that in the various boot programs instead (I think there's a PR
somewhere about using a BIOS call instead of frobbing the keyboard
controller directly that supposedly fixes things like USB keyboards
in the loader.)

John Baldwin <jhb at>  <><
"Power Users Use the Power to Serve"  =

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