Re: Kernel 2.2.* freezes, temporary fix?

Alan Cox (alan@lxorguk.ukuu.org.uk)
Tue, 12 Oct 1999 12:43:18 +0100 (BST)


> I do not think that the APM code has a bug but it seems that it can
> circumvent the freeze by regularly calling printk().

Your APM bios may have timing bugs. It could also be the printk calls
disturb the register allocations so that what is passed to the calls
in the undefined registers is safe. It could even be missing register
clobbers. (especially given the number of biosen who dont save all
the registers they should)

> So I looked into the printk() funktion and saw that printk() uses a lot
> spin_lock_*() and spin_unlock_*. Maybe this way a locked down interrupt
> gets unlocked?

No

> The next point is that I had problems with my system clock and date. The
> clock was too slow and sometimes even seemed to loose a lot more. After
> my apm.c additions the clock is running correctly now. Strange isn't it?

Not really. It also points to APM bios bugs

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