I didn't include linux-ia64 originally. Sorry about that. Here is the 00/14 cover email describing the patch series: http://lkml.org/lkml/2008/7/14/468 Here is the 12/14 ia64 specific bit: http://lkml.org/lkml/2008/7/14/478 Here is the 14/14 patch that Tony is referring to: http://lkml.org/lkml/2008/7/14/482 * Luck, Tony <tony.luck@xxxxxxxxx>: > > Patch 14 is the money patch. It demonstrates why we might > > want to go through all these gyrations. Now that ia64 presents > > *all* physically present CPUs in sysfs, even if they have been > > disabled by firmware, we give userspace a way to poke at those > > CPUs. > > There's only the one bit for "disabled by firmware" ... no extra > space for any extra information. How would userspace know that > it was safe to poke at a disabled cpu? Perhaps firmware disabled > it for some very good reason, and poking at it could cause system > instability. My thought here was that it would be a vendor-specific thing. In patch 14/14 I created: /sys/devices/system/cpu/cpuN/deconfigure (although /sys/device/system/cpu/cpuN/enabled would probably be better) I set up 'deconfigure' to have different implementations based on a DMI, so it is very much an opt-in (especially since it's a Kconfig option). It would be the responsibility of the vendor to provide something safe to poke at. In the sample implementation I gave, nothing happens to the system until the *next* reboot, so it shouldn't cause the current boot any distress. A different implementation of deconfigure/enabled could return an error to userspace if an operation was unsafe. /ac -- 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
