Messages in this thread | | | Date | Tue, 21 Feb 2006 17:44:00 -0800 | From | Andrew Morton <> | Subject | Re: [patch] Re: 2.6.16-rc4-mm1 (bugs and lockups) |
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Stas Sergeev <stsp@aknet.ru> wrote: > > main.c: moved smp_prepare_boot_cpu() call earlier. This > was necessary because otherwise printk() can't print > It checks cpu_online(), which returns false. This change > is consistent with the UP case, where's the boot CPU is > "online" from the very beginning, AFAICS. But again, I am > not entirely sure whether this is safe. >
Yeah, this is scary. Early boot is fragile and complex and architectures might not expect to run smp_prepare_boot_cpu() before setup_arch().
umm, actually it's wrong. i386's smp_prepare_boot_cpu() diddles with per-cpu memory, and that's not initialised at that stage. See the call to setup_per_cpu_areas() a few lines later.
So I'll drop that hunk. How important is it in practice?
If it's purely to make printk print something then perhaps we can do something expedient like:
#ifdef CONFIG_SMP cpu_set(smp_processor_id(), cpu_online_map); /* comment */ #endif
right there in start_kernel()?
(That assumes that smp_processor_id() works at that stage. Surely that's true). - 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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