Date: Mon, 28 May 2001 18:48:07 -0400 (EDT) From: Robert LaThanh <hybrid@ugrad.cs.jhu.edu> To: freebsd-questions@freebsd.org Subject: Rebooting CPU via Keyboard Controller Message-ID: <Pine.GSO.4.05.10105281846200.28707-100000@barley.cs.jhu.edu>
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I just spent about two days trying to figure out why my system would not
reset upon issuing a reboot command. That is, it would hang at
"Rebooting...". My system is an HP Brio 7113N, Intel Celeron 300a with
256MB RAM.
I tried all kinds of things, changing every setting in my BIOS, removing
devices (hard drives, NIC), and even whether different versions of
FreeBSD could reboot with different BIOS settings -- I used to be
running 4.1 and it could reboot fine, then I just did a fresh install of
4.3 and then it couldn't.
Kernel option BROKEN_KEYBOARD_RESET didn't help; the keyboard reset code
wasn't causing problems, it just wasn't working.
Two days of troubleshooting later, I decided to try the the Linux
approach of pulsing the keyboard reset line instead of just tapping it
once. In src/sys/i386/i386/vm_machdep.c::cpu_reset_real() instead of
hitting 0x64 once and waiting, I have it hit 100 times. Here's the
simple change I made and my computer now reboots instead of hanging at
"Rebooting...":
src/sys/i386/i386/vm_machdep.c
485d484
< int i;
505,509c504,505
< for (i=0; i<100; i++) { /* Pulse the keyboard reset line */
< DELAY(50);
< outb(IO_KBD + 4, 0xFE);
< DELAY(50);
< }
---
> outb(IO_KBD + 4, 0xFE);
> DELAY(500000); /* wait 0.5 sec to see if that did it */
Is there any reason that this shouldn't be implemented in the FreeBSD
kernel, I don't see any potential harm it could cause and it may help at
least a few, if not many, people with reset problems.
Robert LaThanh
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