On Fri, 1 Jun 2012, Srivatsa S. Bhat wrote: > From: Nikunj A. Dadhania <nikunj@xxxxxxxxxxxxxxxxxx> > > Convert x86 to use the generic framework to boot secondary CPUs. > > Notes: > 1. x86 manipulates the cpu_online_mask under vector_lock. So, while > converting over to the generic smp booting code, override arch_vector_lock() > and arch_vector_unlock() to lock_vector_lock() and unlock_vector_lock() > respectively. > > 2. In smp_callin(), we allow the master to continue as soon as the physical > booting of the secondary processor is done. That is, we don't wait till the > CPU_STARTING notifications are sent. > > Implications: > - This does not alter the order in which the notifications are sent (i.e., > still CPU_STARTING is followed by CPU_ONLINE) because the master waits till > the new cpu is set in the cpu_online_mask before returning to generic code. > > - This approach is better because of 2 reasons: > a. It makes more sense: the master has a timeout for waiting on the > cpu_callin_map - which means we should report back as soon as possible. > The whole idea of having a timeout is to estimate the maximum time that > could be taken for physical booting. This approach separates out the > physical booting vs running CPU hotplug callbacks and reports back to > the master as soon as physical booting is done. How do you deal with the problem that the master does not come back in time? There is a timeout on the booting side as well. I haven't found out why this timeout exists at all, but we need to take care of that and there is a patch on LKML which removes the panic as this can happen on virt. I really wonder whether the hardware for which this timeout stuff was introduced still exists or whether we can simply get rid of it completely. Also the whole callin/callout mask business wants to be in the generic code. It can be replaced completely by cpu_state, at least that's what I was aiming for. There is no need for several variables tracking the same thing in different ways. Thanks, tglx -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
