On Wednesday 25 July 2007 22:20, david@xxxxxxx wrote: > On Wed, 25 Jul 2007, Len Brown wrote: > > > On Wednesday 25 July 2007 14:48, Linus Torvalds wrote: > > > >> ... ACPI now seems to select CPU hotplug. Why? > > > > ACPI=y SMP=y systems require SUSPEND_SMP=y for system sleep support, > > and that requires HOTPLUG_CPU=y. > > > > Note that ACPI=y SMP=n systems do not need it, > > and thus will not select HOTPLUG_CPU=y > > > >> That is just *broken*. Sure, if you select STR or hibernation, we need CPU > >> hotplug, but just for picking ACPI? Why? > > > > My assumption is that if somebody selects CONFIG_ACPI, > > that 99% of the time, they intend that to include support for > > the ACPI hooks for system sleep states. > > > > Conversely, supporting the 1% of people who don't want it > > isn't worth messing with the 99% who do, nor is > > the burden of yet another config option to maintain and > > #ifdefs in the code. > > so you are saying that you know better then we do what we need? Feel free to share what you know about the benefits vs. the costs of maintaining CONFIG_ACPI_SLEEP as a build option. > some people configure ACPI only becouse their system won't work properly > without it. they have no intention of ever doing a STR or hibernate. I agree. Further, I expect that 100% - (some people %) = 99% If you feel that your system has been degraded because it now includes what used to be excluded under CONFIG_ACPI_SLEEP=n, please let me know how. > > On UP, they'd get ACPI system sleep support 100% of the time > > by default, but on SMP this option had become problematic. > > > > We used to have this: > > > > if ACPI > > ... > > config ACPI_SLEEP > > bool "Sleep States" > > depends on X86 && (!SMP || SUSPEND_SMP) > > depends on PM > > default y > > > > So the poster-child failure was i386/defconfig itself... > > It couldn't support suspend to RAM because it didn't include > > CONFIG_ACPI_SLEEP. Not trivial for a user to select it > > when it doesn't even appear on the menu. It doesn't appear > > because CONFIG_SUSPEND_SMP isn't enabled, but that doesn't > > appear either -- because CONFIG_HOTPLUG_CPU isn't selected. > > so have something like > > config ACPI_SLEEP > select HOTPLUG_CPU if X86 && SMP > select SUSPEND_SMP if X86 && SMP > > instead of makeing it dependant on ACPI. If more config options where better, then this would indeed be an improvement over 2.6.22. But more config options isn't better -- except for "some people":-) thanks. -Len > > Most users don't want that. > > > > So today we have this: > > > > menuconfig ACPI > > ... > > select HOTPLUG_CPU if X86 && SMP > > select SUSPEND_SMP if X86 && SMP > > > > Which I think leads to fewer surprises, and less complicated code. > > (even though using select itself is fraught with peril:-) > > > > thanks, > > -Len > > > > - > > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > > the body of a message to majordomo@xxxxxxxxxxxxxxx > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > Please read the FAQ at http://www.tux.org/lkml/ > > > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > - To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
