consistent hard lockup with recent kernels

[Jon Noack]

On 07/15/04 15:41, Sean McNeil wrote:
> I get a very repeatable hard freeze of the system when I use firefox and
> attempt to download a large iso image.  I've been trying to get a livecd
> image from a gentoo.org mirror (needed for something else, I'm a FreeBSD
> fan, honest!!) ;)
> 
> I suppose this is related to the preemption issues, but don't have
> anything to show for it except my dmegs.  I can't access the system at
> all to see why it is happening.

Yeah, it is most likely bugs uncovered by native preemption.  For now 
you can remask then by commenting out the "#define PREEMPTION" in 
src/sys/<ARCH>/include/param.h and rebuilding your kernel.  Robert 
Watson's comments on this:
"This results in a quite usable kernel, although quite probably more 
poor interrupt handling latency, etc."

You'll see the following warning on boot:
WARNING: Kernel preemption is disabled, expect reduced performance.

An example of this reduced performance is sound issues (slowdowns, pops, 
etc.) when the system is under load (most notably with disk load).

Jon