Messages in this thread | | | Date | Thu, 22 Jan 2004 18:49:26 +0100 | From | Mikael Pettersson <> | Subject | Re: [ACPI] Re: PROBLEM: ACPI freezes 2.6.1 on boot |
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Linus Torvalds writes: > > > On Thu, 22 Jan 2004, Mikael Pettersson wrote: > > > Karol Kozimor writes: > > > > > > diff -Bru linux-2.6.0-test8/arch/i386/kernel/apic.c patched/arch/i386/kernel/apic.c > > > --- linux-2.6.0-test8/arch/i386/kernel/apic.c 2003-10-18 05:43:36.000000000 +0800 > > > +++ patched/arch/i386/kernel/apic.c 2003-10-30 23:17:50.000000000 +0800 > > > @@ -836,8 +836,8 @@ > > > { > > > unsigned int lvtt1_value, tmp_value; > > > > > > - lvtt1_value = SET_APIC_TIMER_BASE(APIC_TIMER_BASE_DIV) | > > > - APIC_LVT_TIMER_PERIODIC | LOCAL_TIMER_VECTOR; > > > + lvtt1_value = APIC_LVT_TIMER_PERIODIC | LOCAL_TIMER_VECTOR; > > > + > > > apic_write_around(APIC_LVTT, lvtt1_value); > > > > What is the purpose of this change? > > I don't remember seeing this before on LKML. (I don't have time to read bugzilla.) > > Hmm.. It does seem to fix things for a couple of people, so it looks > interesting. > > As far as I can tell, the _only_ thing it does is to change the timer base > from "DIV" to "CLKIN". I seem to have misplaced my ia-32 "volume 3" thing, > but I have an old one for a pentium, and that one doesn't actually > haev the timer-base thing at all - and marks those bits as "reserved". > > So it is entirely possible that the only safe value to write there is 0.
Confirmed. Those bits (18 and 19 in LVTT) are marked reserved in the latest IA32 Volume 3. I have no idea where this APIC_TIMER_BASE came from (maybe some ancient discrete LAPIC thing?), but we almost certainly shouldn't write anything but zero to them.
> So I'm inclined to apply the patch, but it would be better if somebody who
I agree. The patch should be applied.
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