Mark Post writes: > If an additional CPU gets DEFINEd (via CP), or configured online (in an > LPAR), you then need to bring it online to the Linux system by echoing a "1" > into /sys/devices/system/cpu/cpu?/online, where ? equals the number of the > CPU, (starting with 0).
Now that Mark's explained nicely what to do, I'd like to follow up with a big fat warning about what *not* to do: do not use "CP DETACH CPU n" to take a virtual CPU out of your guest's configuration once present. A "DETACH CPU" will immediately trigger the effects of a "CP SYSTEM CLEAR" and your guest will be dead in the water with all its memory zeroed. Once a CPU has been DEFINEd into the guest's configuration, only use Linux sysfs to vary it online or offline and don't DETACH it. Another minor warning: I seem to remember one version of SLES9 having problems with hot CPU support. I'm not sure which service pack level; it might even have been before SP1. The symptom was that you could vary offline (and then online) CPUs that existed and were online when the guest was IPLed but if you did a dynamic "CP DEFINE CPU" then a following "echo 1 > .../online" would fail to add it and would leave an uninterruptible process around or something similar. Since the additional_cpus and possible_cpus boot parameters came along, I think things now all work as they should. --Malcolm ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
