Re: Linux v2.5.48

[Manfred Spraul <manfred@colorfullife.com>]

William Lee Irwin III wrote:

>On Mon, Nov 18, 2002 at 07:30:37PM +0100, Manfred Spraul wrote:
>  
>
>>__cpu_up is called in the context of the boot cpu, not in the context of 
>>the new cpu.
>>I think this patch should keep the interrupts disabled until after
>>smp_commenced is set. It's partially tested: bochs boots until all cpus
>>are up and then crashes.
>>I've tested the interrupt flag (pushfl;popfl), noone else enables them.
>>    
>>
>
>That's odd, this should (in theory) enable them:
>
>void __init setup_secondary_APIC_clock(void)
>{
>        local_irq_disable(); /* FIXME: Do we need this? --RR */
>        setup_APIC_timer(calibration_result);
>        local_irq_enable();
>}
>  
>

That's ok.

>
>> +
>> +	local_irq_enable();
>>  	setup_secondary_APIC_clock();
>> 
>
Irqs are enabled just before setup_secondary_APIC_clock();

SMP bootstrap for i386 is
init() [linux/init/main.c()]
-> smp_prepare_cpus()
    -> smp_boot_cpus() [arch/i386/kernel/smpboot.c]
        ->do_boot_cpu()
            -> kick the new cpu.
            new cpu: spinns on the smp_commenced_mask
***** start of critical area: new cpu must not get an irq
-> do_pre_smp_initcalls()
-> smp_init()
    ->cpu_up() [kernel/cpu.c]
        -> CPU_ONLINE_PREPARE notifier call
***** end of critical area: memory for new cpu initialized
        ->__cpu_up() [arch/i386/kernel/smpboot.c]
            -> set_bit(smp_commenced_mask);

--
    Manfred