Messages in this thread | ![/](/images/icornerl.gif) | | Date | Tue, 15 Jul 2003 13:06:19 -0400 | From | Brian Gerst <> | Subject | Re: Interrupt doesn't make it to the 8259 on a ASUS P4PE mobo |
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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.
Use HZ/2 instead. GCC doesn't optimize floating point constants to the same degree it does integers, because it doesn't know what mode (rounding, precision) the FPU is in.
-- Brian Gerst
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