Question with maxcpus= parameter.

From: Zhenzhong Duan
Date: Fri Nov 06 2015 - 00:24:01 EST

Hi Maintainers,

Recently we faced an cpu online issue with maxcpus= parameter.

We want to have 4 cpus onlined at bootup, test 3.8.13-stable on an 72 cpus env with maxcpus=4, I found more cpus than 4 are onlined.
It's the udev scripts make them onlined. But below script exist for a long time.
ACTION=="add", KERNEL=="cpu[0-9]*", RUN+="/bin/bash -c 'echo 1 > /sys/devices/system/cpu/%k/online'"

maxcpu= parameter didn't take effect, so is this a kernel bug? Or that script should be removed?

Btw: 2.6.39 works fine, I checked udev log, seems CPU ADD event is only sent for 4cpus.
Why the difference between 2.6.39 and 3.8.13?

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at