Hi. On Thu, 2005-03-17 at 01:40, Rafael J. Wysocki wrote: > On Wednesday, 16 of March 2005 14:21, Pavel Machek wrote: > > Hi! > > > > I tried to solve long-standing uglyness in swsusp cmp code by calling > > cpu hotplug... only to find out that CONFIG_CPU_HOTPLUG is not > > available on i386. Is there way to enable CPU_HOTPLUG on i386? > > Heh, that's exactly what I was thinking about. ;-) > > AFAICS we don't need the full CPU hotplug to do this. For suspend, we need to > enable the CPU hotplug-related code in sched.c and cpu.c, and we need to > implement the functions __cpu_disable() and __cpu_die() (called from within > cpu.c) on each architecture for which we want swsusp to work on SMP. > > If that's acceptable, the CPU hotplug code in sched.c and cpu.c may be > enabled by changing some #ifdefs there. For example, we could replace the > > #idef CONFIG_CPU_HOTPLUG > > with > > #if defined(CONFIG_CPU_HOTPLUG) || (defined(CONFIG_SOFTWARE_SUSPEND) > && defined(CONFIG_SMP)) > > wherever necessary. > > The implementation of __cpu_disable() and __cpu_die() may be a bit more > tricky, however. In __cpu_disable() we need to save the settings of the local > APIC of each CPU (on x86-64, at least) etc. In __cpu_die() we should give the > "frozen" CPU some "neutral" code to execute, it seems (or "hlt" it?). > > I've looked at the ia64 implementation of these functions, but I haven't fully > understood it yet.
It would be good (32 bit) if you handled MTRRs as well. Putting their save/restore code in the driver model is racy (SMP calls). I've worked around that in Suspend2 by removing the driver model support and making the save/restore calls from the lowlevel code. I think this should be considered the right thing to do. By the way, I'm keen to test this with Suspend2 as well. I would have done so before now, but I didn't realise Zwane had the support done. Regards, Nigel -- Nigel Cunningham Software Engineer, Canberra, Australia http://www.cyclades.com Bus: +61 (2) 6291 9554; Hme: +61 (2) 6292 8028; Mob: +61 (417) 100 574 Maintainer of Suspend2 Kernel Patches http://suspend2.net - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
