Messages in this thread | | | Date | Wed, 06 Nov 2002 12:04:44 -0800 | From | Andrew Morton <> | Subject | Re: Strange panic as soon as timer interrupts are enabled (recent 2.5) |
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"Martin J. Bligh" wrote: > > >> Yes, this caused for me, a completely reliable boot time panic with 2.5.46. > >> The problem is that per_cpu areas aren't initiallised until cpu_up is called, > >> so a cpu cannot now take an interrupt before cpu_up is called. > > > > Rusty's da man on this, but I think the fix is to not turn on > > the interrupts (at the APIC level) until cpu_up() has called > > __cpu_up(). Look at cpu_up(): > > > > ret = notifier_call_chain(&cpu_chain, CPU_UP_PREPARE, hcpu); > > if (ret == NOTIFY_BAD) { > > printk("%s: attempt to bring up CPU %u failed\n", > > __FUNCTION__, cpu); > > ret = -EINVAL; > > goto out_notify; > > } > > > > /* Arch-specific enabling code. */ > > ret = __cpu_up(cpu); > > > > The softirq storage is initialised inside the CPU_UP_PREPARE call. > > So we're ready for interrupts on that CPU when your architecture's > > __cpu_up() is called. And no sooner than this. > > All interrupts, or just softints? >
I don't know. This sequencing really needs to be thought about and written down, else we'll just have an ongoing fiasco trying to graft stuff onto it.
In this case I'd say "all interrupts". The secondary really should be 100% dormant until all CPU_UP_PREPARE callouts have been run and have returned NOTIFY_OK.
At least, that's how I'd have designed it. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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