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Re: Question : grub commands

On Tue, Aug 15, 2006 at 06:27:32AM +0200, Hans wrote:
> Sorry, I maybe did not ask correctly. It is not the problem, that the time is 
> not shown correctly. The background is, that other timings are running in 
> double speed, too (i.e. keyboard clock and some other). This is a known 
> problem on AMD mobile processors and was discussed in earlier days. The 
> solution of it, was to add "disable_timer_pin_1" in the boot vcommand on grub 
> or lilo. Now I read about adding "noapictimer" should solve this, too. My 
> question aimed to an technical answer, if the commands "disable_timer_pin_1" 
> and "noapictimer" are doing the same, or if they both solve the mentioned 
> problem in different ways.

I believe the problem occoured with ATI chipsets on laptops.  As far as
I have understood it, the problem is that the timer interrupts occour
both on the 8259 interrupt controller, and through the apic.  I believe
'disable_timer_pin_1' makes the kernel ignore the 8259 interrupt for the
timer, and that 'noapictimer' ignores the apic interrupt for the timer.
Since the problem seems to be getting two interrupts for every timer
event, one for each interrupt method, it makes sense that disabling
either one will solve the problem.  It doesn't matter which one you
disable as long as you disable one of the two.

It really looks like a bug in the design of the chipset, although it may
just be that the BIOS/ACPI tables are done wrong, which is rather common
it seems.  Too often the ACPI tables for windows work, but are
incomplete or wrong for other operating systems.  Apparently on such
systems, telling linux to lie to acpi and pretend to be windows xp often
solves such strange problems.

Len Sorensen

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