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feugan
Contributor
Contributor

The host high-resolution timer device (/dev/rtc) is not available (Operation not permitted) on Ubuntu 8.10

Hi all.

Whenever I start a VM on my VMware workstation (version 5.5.9), I get the following error message:

The host high-resolution timer device (/dev/rtc) is not available (Operation not permitted). Without this device, the guest operating system can fail to keep time correctly. For more information, see .

My VM's also run very slowly and time seems to lag behind.

I've checked that the /dev/rtc device does exist. (It's a symlink to /dev/rtc0 ).

I've also tried to run vmware as root in case it was a permissions problem, but I still get exactly the same error.

I saw the following logs in dmesg which might be related (Sorry about formatting, I'm not sure how to get it right):

[http://132455.983263|http://132455.983263] [9648]: host clock rate change request 0 -> 19
[http://132455.984987|http://132455.984987] [9648]: host clock rate change request 19 -> 1043
[http://132455.985017|http://132455.985017] [9648]: /dev/rtc enable interrupt failed: -1
[http://132501.392795|http://132501.392795] [9648]: host clock rate change request 19 -> 1024
[http://132501.393471|http://132501.393471] [9648]: /dev/rtc enable interrupt failed: -1
[http://132501.394903|http://132501.394903] [9648]: host clock rate change request 19 -> 1043
[http://132501.394921|http://132501.394921] [9648]: /dev/rtc enable interrupt failed: -1

Kernel version: 2.6.27-11-generic

This error (and degraded performance) is really annoying.

Any advice would be appreciated.

Thanks,

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27 Replies
moenchmeyer
Enthusiast
Enthusiast

I tried the settings in "/proc/sys/dev/hpet/max-user-freq" recommended by ellicollins on my Opensuse 11.1 system. It did not do any harm. However, it does not seem to do any good either - at least not after working an hour with the system. I do not get the feeling that my Win XP guest is working any faster. And regarding the warning - it does not disappear:

I can reproduce the warning at any time by connecting a USB 2.0 scanner to my system. Whenever I start my first scan the warning about the "not available" /dev/rtc appears. And it appears despite setting the "max-user-freq" to 1024 !

I do not know how Ubuntu or Fedora will react, but I suspect that there won't be a big difference.

And the question remains: Why don't we get some comments from VMware on the subject ?

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moenchmeyer
Enthusiast
Enthusiast

Elicollins, as you mentioned the difference between rtc and hpet : Could you explain to us what the difference is ?

I googled "/dev/rtc /dev/hpet" and after reading it seems to me that something has changed fundamentally regarding the handling of timer devices (with kernel 2.6.27 ?). Furthermore there also are other programs (especially in the field of video/audio) which suffer from the disappearance of /dev/rtc and the corresponding "/proc/sys/dev/rtc/max-user-freq". So maybe this is not only a VMware problem ....

See e.g. "http://forum.linuxmce.org/index.php?action=printpage;topic=6800.0"

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blackpuma
Contributor
Contributor

Doing

#

echo 1024 > /proc/sys/dev/hpet/max-user-freq

as root doesn't seem to affect anything on Fedora 11; I still get the message. (Yeah, it's not supported, but it works 99% of the time; this is the 1%.)

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tacchino
Contributor
Contributor

I've got no changes with this action, the message persists.

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ScottNZ
Contributor
Contributor

No luck here either. My host is Ubuntu Jaunty x86_64; kernel 2.6.28-15-generic. I tried:

<code># echo 1024 /proc/sys/dev/hpet/max-user-freq</code>

Non root user can read new value (1024), but eventually I see "/dev/rtc open failed: -13" in dmesg output (sometime after starting guest OS and apps).

Scott

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janknepper
Contributor
Contributor

Query:

sysctl -n dev.hpet.max-user-freq

Set:

sysctl -w dev.hpet.max-user-freq=1024

/etc/sysctl.conf

  1. VMware fix

dev.hpet.max-user-freq = 1024

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atoms
Contributor
Contributor

Received the same message for Ubuntu 8.04.3 x64 2.6.24-24.

If the vmware error message mentions /dev/rtc you can check and test with:

Query:

sysctl -n dev.rtc.max-user-freq

Set:

sysctl -w dev.rtc.max-user-freq=1024

And if that works (works for me!) edit the sysctl.conf:

gksudo gedit /etc/sysctl.conf

...add the following line to the end of the file:

dev.rtc.max-user-freq = 1024

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pmorch
Enthusiast
Enthusiast

http://communities.vmware.com/message/1468277#1468277 shows the solution that worked for me on a similar issue:

$ sudo bash -c 'echo 1024 > /sys/class/rtc/rtc0/max_user_freq'

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