* Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>: > On Mon, 2008-07-14 at 20:34 -0600, Alex Chiang wrote: > > Populate the cpu_enabled_map correctly. > > > > Note that this patch does not actually make any decisions based > > on the contents of the map. > > > > However, as the map is presented via sysfs in: > > > > /sys/devices/system/cpu/ > > > > It should be populated correctly. > > Care to educate me on the difference between online_map and > enabled_map ? enabled_map is closer conceptually to present_map than online_map. present_map are CPUs that are actually plugged in online_map are CPUs that have had cpu_up() called on them; ie. schedulable enabled_map is somewhere inbetween -- the CPUs are plugged in, but we don't want to cpu_up() them. On hp ia64 systems, these CPUs are disabled by system firmware. Currently, a user can only configure/deconfigure the CPUs from the system firmware interface. By providing a sysfs interface for these CPUs, we can allow the user to configure/deconfigure them from userspace. More realistically, higher level managability software now has an OS-level interface to interact with these CPUs. Might this be useful for ppc and your hypervisor based architecture? I could imagine your hypervisor telling the kernel about all the physically present CPUs, but then you would be able to have finer grained control using the enabled_map. I haven't studied your code in depth, so maybe you can just do everything with pure online/offline, but at least on my platforms, there are use-cases where we might want something in-between. Thanks. /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
