timer irq setup

timer irq setup

[Thomas Koeller]

In arch/mips/kernel/traps.c, per_cpu_trap_init() contains
code to set up the global cp0_compare_irq variable. Does
this make sense? I'd say that either the irq setup should
be moved to trap_init(), or cp0_compare_irq should be
changed to a per-cpu variable, depending on what the original
intention was.

tk
-- 
Thomas Koeller
thomas at koeller dot dyndns dot org

Re: timer irq setup

[Ralf Baechle]

On Mon, Dec 17, 2007 at 11:35:22AM +0100, Thomas Koeller wrote:

> In arch/mips/kernel/traps.c, per_cpu_trap_init() contains
> code to set up the global cp0_compare_irq variable. Does
> this make sense? I'd say that either the irq setup should
> be moved to trap_init(), or cp0_compare_irq should be
> changed to a per-cpu variable, depending on what the original
> intention was.

Technically it would be legal to route the timer interrupt to a different
interrupt for each of possibly multiple processors, that's why it's done
in per_cpu_trap_init().

Obviously the rest of the code isn't quite there and also to best of my
knowledge all actual implementations use the same interrupt across all
cores.  So something like a global variable and a paranoia check in
per_cpu_trap_init() to ensure all CPUs really use the same interrupt
would seem reasonable.

  Ralf