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When I log in to a remote CentOS 7 HOST server using Putty and perform actions with GUEST virtual machines using kvm (virsh, virt-install, etc), I am not alerted to certain errors.

Then, when I visit the physical location of the physical HOST box and view the monitor attached to the host box, I sometimes find the screen filled with repeating error messages that were not visible to the remote Putty sessions.

For example, when I visited the physical box today, I saw that the following error message had repeated on every line of the physical screen:

kvm [nnnn] vcpu0 unhandled rdmsr

The numbers for nnnn changed in some of the lines, and it looked as if countless pages of these errors had been lost as the screen continued to overflow.

What specific commands would need to be typed in order for these error messages to be accessible via Putty? Does any specific output need to be turned on? Or diverted into a text file? And how can these messages trigger alert in the Putty session?

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If I understand well what you are searching for, these messages should be in the dmesg log.

  • OK. Typing dmesg showed the information. But it seems that I would have to have a second putty session with dmesg running in order to notice these messages while running commands in the first putty window. Can you suggest a better way to be alerted of the information in these messages? – CodeMed Mar 29 '17 at 4:27
  • It is a good programming/scripting practice to check for errors after running function/command. So you can either check new messages in dmesg manually, follow the logs in the file itself /var/log/dmesg or write some script that will alert you about new messages (for example in PS1 prompt). – Jakuje Mar 29 '17 at 7:19

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