The Lowest Priority Bug Ever? (/etc/udev/rules.d/z10-xen-vcpu-hotplug.rules)

bnerickson

I'm unsure where to report this, but syslog reports the following warning when a VM starts:

(UDEV-WORKER)   cpu0: Process '/bin/sh -c '[ -e /dev/xen/xenbus ] && [ -e /sys/devices/system/cpu/cpu0/online ] && echo 1 > /sys/devices/system/cpu/cpu0/online'' failed with exit code 1.

This is because /sys/devices/system/cpu/cpu0/online does not exist. I'm assuming that this may be expected, so I think the udev rule could be rewritten as follows to avoid spitting out an error:

# cat /etc/udev/rules.d/z10-xen-vcpu-hotplug.rules
ACTION=="add", SUBSYSTEM=="cpu", RUN+="/bin/sh -c 'if [ -e /dev/xen/xenbus ] && [ -e /sys$devpath/online ]; then echo 1 > /sys$devpath/online; fi'"

bnerickson

Oh, syslog also reports the following harmless warning:

Configuration file /etc/udev/rules.d/z10-xen-vcpu-hotplug.rules is marked executable. Please remove executable permission bits. Proceeding anyway.  4

So presumably the executable bits should be removed from this file as well.

For what it's worth:

dom0 version:

xcp-ng-release-config-8.3.0-35.x86_64
xcp-ng-deps-8.3-13.noarch
xcp-ng-plymouth-theme-1.1.0-5.xcpng8.3.noarch
xcp-ng-xapi-plugins-1.15.0-1.xcpng8.3.noarch
xcp-ng-generic-lib-1.1.1-4.xcpng8.3.x86_64
xcp-ng-release-presets-8.3.0-35.x86_64
xcp-ng-release-8.3.0-35.x86_64
xcp-ng-pv-tools-8.3-15.xcpng8.3.noarch

VM Details:
Kernel:

$ uname -a
Linux fqdn 6.12.0-124.27.1.el10_1.x86_64 #1 SMP PREEMPT_DYNAMIC Thu Jan 15 13:51:25 UTC 2026 x86_64 GNU/Linux

OS:

$ cat /etc/os-release 
NAME="Rocky Linux"
VERSION="10.1 (Red Quartz)"
ID="rocky"
ID_LIKE="rhel centos fedora"
VERSION_ID="10.1"
PLATFORM_ID="platform:el10"
PRETTY_NAME="Rocky Linux 10.1 (Red Quartz)"
ANSI_COLOR="0;32"
LOGO="fedora-logo-icon"
CPE_NAME="cpe:/o:rocky:rocky:10::baseos"
HOME_URL="https://rockylinux.org/"
VENDOR_NAME="RESF"
VENDOR_URL="https://resf.org/"
BUG_REPORT_URL="https://bugs.rockylinux.org/"
SUPPORT_END="2035-05-31"
ROCKY_SUPPORT_PRODUCT="Rocky-Linux-10"
ROCKY_SUPPORT_PRODUCT_VERSION="10.1"
REDHAT_SUPPORT_PRODUCT="Rocky Linux"
REDHAT_SUPPORT_PRODUCT_VERSION="10.1"