Red Hat Bugzilla – Bug 160833
The /dev/cpu/microcode node required by the microcode_ctl initscript is not created
Last modified: 2015-01-04 17:20:17 EST
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Description of problem:
If I run the following command: service microcode_ctl start I get an error saying that /dev/cpu/microcode isn't available. This, most notably, happens at boot up.
If I add the following lines to the initscript, everything works fine:
mkdir -p `dirname $DEVICE`
mknod -m 600 $DEVICE c 10 184
Version-Release number of selected component (if applicable):
kernel-utils 2.4 13.1.66
Steps to Reproduce:
service microcode_ctl start
A similar bug was reported for FedoraCore 3 (#157672). That's probably where the
problem stems from.
Created attachment 116092 [details]
patch for /etc/rc.d/init.d/microcode_ctl
Nope, that's not the problem.
In RHEL4 U1, udev correctly creates the /etc/cpu/microcode device file when the
microcode module is loaded. The problem is that /etc/rc.d/init.d/microcode_ctl
tests for the presence of the device file *before* it attempts to modprobe the
microcode module. As a result, if the microcode module isn't already loaded
(and it won't be, if the system's booting up), /etc/rc.d/init.d/microcode_ctl
doesn't find the /etc/cpu/microcode device file, and bombs out.
Here's a patch for /etc/rc.d/init.d/microcode_ctl that fixes the problem. (I
think this operation ordering makes the most sense.)
I've tried this patch, but I am still getting the same microcode device /dev/cpu/microcode doesn't exist?
error on boot. It seems there is a significant delay (more than 3 seconds) in udev creating the device files,
so I'm making the script sleep for 4 seconds after the modprobe command. I'm sure there's a more
efficient way to handle this.
I think the significant delay is startup-specific. If you run "modprobe
microcode" on quiescent system, it only takes a fraction of a second for the
device node to appear.
Probably a better way to handle it is to keep running "usleep 250000" until the
device node appears, with a reasonable timeout (e.g., 10 seconds) before aborting.
This happen to me also here on an RHEL4 system.
1) without the patch #116092, such message is been shown, without, it quits
quietly which is ok, because it's an Athlon CPU.
2) related to #9: there is already a delay included in the script:
while [ ! -c $DEVICE ]; do
[ $lt -gt 5 ] && break;
Anyway, looks like since introducing udev and its asynchron device creation this
rises up to a common problem, it hit me also loading a framebuffer module and
try to execute fbset after the modprobe call in a script...
I have a similar problem in FC4 (upgraded from FC3 if that is relevant).
I was able to fix this issue on FC4 by creating the executable file named
/etc/sysconfig/modules/microcode.modules with the following content:
After that microcode_ctl works fine when booting up.
*** Bug 166210 has been marked as a duplicate of this bug. ***
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on the solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.
Created attachment 120554 [details]
patch for microde_ctl, checks sufficient delay
The delay of 5 seconds is insufficient on my Dell PowerEdge 1850
with RHEL ES4 update2 (includes kernel-utils-2.4-13.1.69).
I tried several times with this patch, it needs 11 seconds.
I also have a Dell PowerEdge 1850 and 5 seconds wasn't enough. With kamo's
patch, I did three test boots and it took either 9 or 10 seconds. The 1850 has
two Intel Xeon 3.2Ghz CPUs.
I also have a PowerEdge 850 and it seems to work fine on that with the 5 second