Messages in this thread | | | Date | Mon, 29 Apr 2013 18:11:03 -0700 | From | John Stultz <> | Subject | Re: [patch 07/15] clocksource: Provide unbind interface in sysfs |
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On 04/25/2013 01:31 PM, Thomas Gleixner wrote: > With the module refcount held for the current clocksource there is no > way to unload the module. > > Provide a sysfs interface which allows to unbind the clocksource. One > could argue that the clocksource override could be (ab)used to do so, > but the clocksource override cannot be used from the kernel itself, > while an unbind function can be used to programmatically check whether > a clocksource can be shutdown or not. > > The unbind functionality uses the new skip current feature of > clocksource_select and verifies that a fallback clocksource has been > installed. If the clocksource which should be unbound is the current > clocksource and no fallback can be found, unbind returns -EBUSY. > > This does not support the unbinding of a clocksource which is used as > the watchdog clocksource. No point in fostering crappy hardware.
So.. if the clocksource you want to unbind is the highest rated continuous clocksource that doesn't need a watchdog (basically what's likely to be in-use and required to be unbinded), its likely to be selected as the watchdog already.
ie: on a system that has only HPET/ACPI_PM, you can't unbind HPET, since its a watchdog.
Or are you really wanting to prohibit this functionality for all CONFIG_CLOCKSOURCE_WATCHDOG hardware, which would be easier to do via build time ifdefs?
thanks -john
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