Messages in this thread | | | Date | Tue, 15 Jul 2003 11:31:17 -0400 (EDT) | From | "Richard B. Johnson" <> | Subject | RE: Interrupt doesn't make it to the 8259 on a ASUS P4PE mobo |
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On Tue, 15 Jul 2003, Kathy Frazier wrote:
> Thanks for your reply, Andi. > > >> We have a proprietary PCI board installed in a (UP) system with an ASUS > P4PE > >> motherboard (uses Intel 845PE chipset). This system is running Red Hat > 9.0 > > >Have you checked the 845 errata sheets on the Intel website? > >Perhaps it is some known hardware bug. > > >One thing you could try is to use Local APIC / IO APIC interrupt processing > >instead of 8259. > > Our hardware engineer has combed the Intel and ASUS websites, but found > nothing. I'll give the APIC a try and see if I get different results and > let you know. > > >> > >> /* start timer */ > >> dmatimer.expires = jiffies + 0.5*HZ; > > >That's a serious bug. You cannot use floating point in the kernel. > >It will corrupt the FP state of the user process. > > HZ on the INTEL platform is 100, so this should simply add 50 to the current > value of jiffies. Besides, assigning the value to the unsigned int field > (expires) will truncate it to an integer anyway. Is there a more > appropriate way to handle a short timeout?
It will truncate it at runtime.
I suggest
dmatimer.expires = jiffies + HZ/2;
Also, you you need to use the time_before() macro, like
while ( time_before(jiffies, dmatimer.expires) ) do_something();
... so you don't have a timer-wrap problem during jiffie rollover if you haven't already done so (I don't have your source here).
> > Thanks, > Kathy
Cheers, Dick Johnson Penguin : Linux version 2.4.20 on an i686 machine (797.90 BogoMips). Why is the government concerned about the lunatic fringe? Think about it.
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