Messages in this thread | | | Date | Tue, 16 Dec 2003 08:57:45 -0500 (EST) | From | "Richard B. Johnson" <> | Subject | Re: Catching NForce2 lockup with NMI watchdog |
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On Tue, 16 Dec 2003, Maciej W. Rozycki wrote:
> On Mon, 15 Dec 2003, George Anzinger wrote: > > > > Hmm, you could have simply asked... ;-) Anyway, an inclusion is doable, > > > I guess. > > > > I suspect I did, but most likey the wrong place. In any case, I would like to > > think that "read the source, Luke" is the right answer. > > Certainly it is, but not necessarily the only one. ;-) > > > So, while I am in the asking mode, is there a simple way to turn off the PIT > > interrupt without changing the PIT program? I would like a way to stop the > > interrupts AND also stop the NMIs that it generates for the watchdog. I suspect > > that this is a bit more complex that it would appear, due to how its wired. > > Well, in PC/AT compatible implementations, the counter #0 of the PIT has > its gate hardwired to active, so you cannot mask the PIT output itself. > So the only other choices are either reprogramming the counter to a mode > that won't cause periodic triggers (which is probably the easiest way, but > you don't want to do that for some purpose, right?) or reprogramming > interrupt controllers not to accept interrupts arriving from the PIT. > > Note that Linux may behave strangely then. ;-) >
Masking OFF the timer channel 0 in the interrupt controller is probably the easiest thing to do. The port is read-write, and the OCW default to having it accessible.
movw $0x21, %dx # Controller 0, mask register inb %dx, %al # Get mask orb $1, %al # Mask off bit 0 outb %al, %dx # Write it back
You can reenable by:
movw $0x21, %dx inb %dx, %al andb $~1, %al outb %al, %dx
With port numbers less that 256, you actually don't need the DX register but I forget if the AT&T assembler needs a $ before the port number when doing this.
Cheers, Dick Johnson Penguin : Linux version 2.4.22 on an i686 machine (797.90 BogoMips). Note 96.31% of all statistics are fiction.
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