Messages in this thread | | | Date | Wed, 8 Feb 2006 19:05:12 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH] percpu data: only iterate over possible CPUs |
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Rik van Riel <riel@redhat.com> wrote: > > On Sun, 5 Feb 2006, Linux Kernel Mailing List wrote: > > > [PATCH] percpu data: only iterate over possible CPUs > > This sched.c bit breaks Xen, and probably also other architectures > that have CPU hotplug. I suspect the reason is that during early > bootup only the boot CPU is online, so nothing initialises the > runqueues for CPUs that are brought up afterwards. > > I suspect we can get rid of this problem quite easily by moving > runqueue initialisation to init_idle()...
We've hit this snag with a few architectures. They're setting up cpu_possible_map too late. It's never been clearly defined.
sched_init() is called here:
asmlinkage void __init start_kernel(void) { ... printk(linux_banner); setup_arch(&command_line); setup_per_cpu_areas(); smp_prepare_boot_cpu(); sched_init();
Users of __GENERIC_PER_CPU definitely need cpu_possible_map to be initialised by the time setup_per_cpu_areas() is called, so I think it makes sense to say "thou shalt initialise cpu_possible_map in setup_arch()".
I guess Xen isn't doing that. Can it be made to? - 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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