Messages in this thread | | | Date | Thu, 16 Feb 2006 00:14:09 +0000 | From | Russell King <> | Subject | Re: SMP BUG |
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On Wed, Feb 15, 2006 at 03:46:34PM -0800, Andrew Morton wrote: > Russell King <rmk+lkml@arm.linux.org.uk> wrote: > > > > On Wed, Feb 15, 2006 at 03:30:13PM -0800, Andrew Morton wrote: > > > Linus Torvalds <torvalds@osdl.org> wrote: > > > > That said, nobody seemed to comment on this patch by Rik, which seemed to > > > > be a nice cleanup regardless of any other issues. > > > > > > I thought that patch wasn't a good one. The runqueues should be > > > initialised in sched_init(). init_idle() is called from fork_idle() which > > > is called from the bowels of arch code. I'm not sure that it gets called > > > at all if !SMP (which seems strange). > > > > Wouldn't it make sense to do this initialisation in a CPU_UP_PREPARE > > notifier, if not already done? > > > > Could be - we have a couple of notifier handlers in sched.c already, > although they're inside awkward CONFIG_* wrappers. > > But architectures need to initialise cpu_possible_map in setup_arch() > anyway, because we immediately call setup_per_cpu_areas(), which needs to > know which CPUs are possible so it will only allocate memory for them. > > Yes, architectures can override the generic setup_per_cpu_areas(), but the > same argument applies: they don't want to be allocating memory for > !possible CPUs. > > So I think it's sanest to say that the arch shalt initialise cpu_possible_map > in setup_arch().
Is that the only thing which needs to be initialised early for SMP, or are there other changes with early SMP init looming?
The reason I ask is that the cleanest solution for ARM would be to introduce yet another initialisation function for MP platforms to implement, which setup_arch() will call after the initial page tables have been setup. Hence, I'm wondering if the platform specific parts could be simplified by moving more stuff earlier.
-- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: 2.6 Serial core - 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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