linux-kernel - ia64 start secondary cpus: what's the first line where interrupts can arrive?

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Message-ID: <48C39B42.4080504@colorfullife.com>
Date:	Sun, 07 Sep 2008 11:13:38 +0200
From:	Manfred Spraul <manfred@...orfullife.com>
To:	linux-ia64@...r.kernel.org
CC:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	tony.luck@...el.com
Subject: ia64 start secondary cpus: what's the first line where interrupts
 can arrive?

Hi,

For my rcu implementation, I try to figure out how the boot process for 
secondary cpus works.

arch/ia64/kernel/smpboot.c contains the following code:
> static void __cpuinit
> smp_callin (void)
> {
> [snip]
>         per_cpu(cpu_state, cpuid) = CPU_ONLINE;
>         spin_unlock(&vector_lock);
>         ipi_call_unlock_irq();
> <<<<<
> <<<<< ipi_call_unlock_irq() does local_irq_enable()
> <<<<<
>         smp_setup_percpu_timer();
>
>         ia64_mca_cmc_vector_setup();    /* Setup vector on AP */
>
> #ifdef CONFIG_PERFMON
>         pfm_init_percpu();
> #endif
>
>         local_irq_enable();
> <<<<<
> <<<<< Another local_irq_enable().
> <<<<<
Which of these two local_irq_enable()'s is the right one?

And: IMHO it's unclean to abuse ipi_call_unlock_irq() to enable the 
local interrupts.
What about the attached patch? Untested due to lack of test hardware.

--
    Manfred

View attachment "patch-ia64-smpboot" of type "text/plain" (869 bytes)