Computer hangs on reboot

Andrey Shuvikov mr.hyro at
Sat Jun 2 04:12:54 UTC 2007

On 5/28/07, Andrey Shuvikov <mr.hyro at> wrote:
> Hi,
> I posted this question originally to freebsd-acpi list but without
> much luck. Besides I'm not sure it's ACPI problem.
> I have a computer with SIS630E-based PCChips motherboard (M787CL+) and
> FreeBSD 6.2 (lately I upgraded to RELENG_6, but it didn't help). The
> problem is that when I try to reboot it just hangs. The last line I
> see on the screen is "Rebooting...", then some vertical lines move
> across the screen (maybe video mode switch or something like that),
> and that's it.
> I tried to add some debug output to cpu_reset_real() code:
>  printf("cpu_reset_real(): before keyboard reset\n");
>  outb(IO_KBD + 4, 0xFE);
>  printf("cpu_reset_real(): after keyboard reset\n");
> Then the last two lines I see on the screen when I try to reboot are:
> cpu_reset_real(): before keyboard reset
> c
> Also I tried to set BROKEN_KEYBOARD_RESET option but nothing changed
> (except I didn't see these debugging messages, obviously).
> The dmesg is at
> Booting with ACPI disabled doesn't help, neither does setting
> hw.acpi.disable_on_reboot and hw.acpi.handle_reboot to 1 (either one
> or both).
> Does anybody know how to fix this?
> Thank you,
> Andrey

Tried to investigate further... Added code to print keyboard
controller output port to make sure A20 is open. Got 0x0B. Does it
mean that A20 is really open? If A20 is controlled by some kind of
"Fast A20" option, will keyboard controller still show the right
status? And what else can I check?


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