I've been trying to track down what makes ACPI kill the system in 2.4.1.
In the acpi_idle function (drivers/acpi/cpu.c), it seems to spend most
of its time with interrupts disabled, only enabling them to check
need_resched occasionally.
In the 'sleep1' state the following code is executed:
for (;;) {
unsigned long time;
unsigned long diff;
__cli();
if (current->need_resched)
goto out;
time = acpi_read_pm_timer();
safe_halt();
diff = acpi_compare_pm_timers(time, acpi_read_pm_timer());
if (diff > acpi_c2_enter_latency
&& acpi_max_c_state >= 2)
goto sleep2;
}
This looks wrong to me. It's basically looping with interrupts
disabled. I can't see how current->need_resched could be updated at
all, so the loop will only terminate when the PM timer tells it to.
Isn't disabling interrupts a bad thing anyway? Wouldn't it be better to
leave them enabled (this is uniprocessor only so there shouldn't be
concurrency issues).
Tony
--
The only secure computer is one that's unplugged, locked in a safe,
and buried 20 feet under the ground in a secret location... and i'm
not even too sure about that one"--Dennis Huges, FBI.
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