Messages in this thread | | | Date | Mon, 13 Nov 2006 21:07:08 +0530 | From | Gautham R Shenoy <> | Subject | Re: [RFC] [PATCH] cpu_hotplug on IBM JS20 system |
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On Mon, Nov 13, 2006 at 02:09:26PM +0100, Heiko Carstens wrote: > > Since we are not supported by hardware for cpu hotplug. I have developed > > the patch which will disable cpu hotplug on IBM bladecentre JS20. Please > > let me know your comments on this please. > > > +extern int cpu_hotplug_disabled; > > +extern struct mutex cpu_add_remove_lock; > [...] > > + if(rtas_stop_self_args.token == RTAS_UNKNOWN_SERVICE) { > > + mutex_lock(&cpu_add_remove_lock); > > + cpu_hotplug_disabled = 1; > > + mutex_unlock(&cpu_add_remove_lock); > > + } > > + > > #endif /* CONFIG_HOTPLUG_CPU */ > > #ifdef CONFIG_RTAS_ERROR_LOGGING > > rtas_last_error_token = rtas_token("rtas-last-error"); > > You should add a function to kernel/cpu.c which you can call in order to > disable cpu hotplug instead of exporting its private data structures.
Yup. Also, considering the fact that enable_nonboot_cpus() can reset the cpu_hotplug_disabled flag, I would suggest the following:
a) create one additional state for cpu_hotplug_disabled, something like
#define PERMANENTLY_DISABLED -1
b) Define a function kernel/cpu.c
void disable_cpu_hotplug_perm() { cpu_hotplug_disabled = PERMANENTLY_DISABLED; }
and call it in rtas.c
c) Check for status of cpu_hotplug_disabled in functions cpu_up, cpu_down, enable_nonboot_cpus and disable_nonboot_cpus and if cpu_hotplug_disabled == PERMANENTLY_DISABLED, return bypassing further code.
Thoughts?
Regards, gautham. -- Gautham R Shenoy Linux Technology Center IBM India. "Freedom comes with a price tag of responsibility, which is still a bargain, because Freedom is priceless!" - 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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