Subject: Re: System hangs after BIOSCALL
To: Frank van der Linden <>
From: Brian Clough <>
List: tech-kern
Date: 10/17/2001 14:20:21
It looks like I was spending too much time in real mode.  I was hanging because I
had a timer interrupt that never got serviced.  IRQ0 probably got hit while I was
in real mode, and then just sat there "pending" when I returned to protected.

I solved the problem by calling splclock() before the BIOSCALL and splx() after. 
That kept the timer interrupt masked while I was in real mode.

Manuel Bouyer wrote:
> On Tue, Oct 16, 2001 at 05:45:29PM +0200, Frank van der Linden wrote:
> > Hm, just noticed that there already is an explicit cli in biostramp.S.
> > So disabled interrupts should not be the problem, even though being
> > stuck in a hlt is a symptom of that..
> Maybe it's just the clock interrupts that don't happen any more ?
> could the hardware timer be stopped by the BIOS call ?
> --
> Manuel Bouyer <>
> --

Brian Clough
OS Development Group, Norwood, MA