December 2021 - Users - libvirt List Archives

Qemu monitor info tlb gives unable to encode message payload
by Philipp Klocke 09 Dec '21

09 Dec '21

Hi, the command virsh qemu-monitor-command ubuntu_vm --hmp --cmd "info tlb" fails with "error: Unable to encode message payload". I found a bugtracker entry for a similiar error [1], but I don't if this is the same error (message too large). I also don't know how large an info tlb message is. Preferably I would not have to recompile libvirt just to issue this monitor command.. Then I thought about circumventing the error by connecting directly to the qemu monitor via netcat, but I found a thread [2] that says I cannot add my own "-monitor tcp:..." to the Qemu commandline arguments. Could someone help me with this? Best, Philipp [1] https://bugzilla.redhat.com/show_bug.cgi?id=1440683 [2] https://libvirt-users.redhat.narkive.com/E0UTmdhU/is-there-a-way-to-disable…

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No QXL in CentOS 9 Stream?
by lejeczek 07 Dec '21

07 Dec '21

Hi. There seems to be no QXL (and Spice?) support in versions from CentOS 9 repos. Would anybody know if that intended, because something else replaces qxl perhaps? thanks, L

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Libvirt Snapshot Question
by Elias Mobery 03 Dec '21

03 Dec '21

Hi everybody! I'm using a snapshot purely for writes and was wondering if it's possible to clear/empty the snapshot after it reaches a certain size? Created with: virsh snapshot-create-as --disk-only I tried deleting and recreating it but get an error at deletion: virsh snapshot-delete Error: source for disk 'vda' is not a regular file I also tried virsh snapshot-create-as --no-metadata --disk-only But the same error as above pops up when trying to delete. Any ideas?

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qemu-img create with extended_l2=on, followed by virt-install
by Richard Taubo 02 Dec '21

02 Dec '21

Hi! I have read the following blog post: https://blogs.igalia.com/berto/2020/12/03/subcluster-allocation-for-qcow2-i… and watched the video displayed there. 1) To make qcow2 as fast as possible, does it make sense to do the following: [#] qemu-img create -f qcow2 -o extended_l2=on,cluster_size=128k my_image.qcow2 1000GB And then: [#] virt-install —name=MyVM --disk path=my_image.qcow2,size=1000 . . . Will this overwrite the qcow2 file already created or will it keep its characteristics? Does it make sense? 2) I wont’t be moving the VM around much and have the space I need, so I wonder if it will be faster to do the following: [#] qemu-img create -o preallocation=full -f qcow2 my_image.qcow2 1000GB And then: [#] ] virt-install —name=MyVM --disk path=my_image.qcow2,size=1000,bus=scsi,sparse=false . . . (Running bus=scsi so I can trim the image ). I could use a dedicated disk for the VM instead of using qcow2, but I like the flexibility of qcow2. Thanks a lot for any information about this! :-) Best regards, Richard Taubo

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