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carcajou
Apprentice
Joined: 10 Jun 2008
Posts: 250
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 Posted: Thu Mar 06, 2025 8:43 am Post subject: Qemu vs Libvirt for everday desktop use? |
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Hello all.
Approx. 2 years ago I switched to "raw" qemu/kvm from virt-manager (libvirt). Libvirt seemed an enterprise-grade overkill for my use case where I am running:
- a single Windows 10 VM (mainly because of MS Office and legacy games) and
- some Linux/BSD throwaway VMs either in desktop mode or "container-style" where I SSH into for terminal based tools.
I am not doing anything "funny", it is mostly to keep my Gentoo host clean, especially when I need to try out something fast, so binary distros have an advantage here. I literally have 2 bash aliases/scripts (one for Windows which I occasionally run in -snapshot mode), executed as normal user, which I can share this evening (in case you can give me some feedback or a tip).
My questions:
1) is there any reason not to use raw qemu? Like performance-wise and security-wise (for my use case)? The worst (most dangerous) thing I do on these desktop-Linux-VMs is opening a shady website while mostly using VPN and occasional torrent-ing.
2) do you maybe have some tips regarding performance/security/setup/user-interface tuning of Qemu and related options?
Thank you very much for your help and feedback. |
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szatox
Advocate
Joined: 27 Aug 2013
Posts: 3541
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| Posted: Thu Mar 06, 2025 11:16 am Post subject: |
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| Quote: | | 1) is there any reason not to use raw qemu? |
Protecting your sanity.
Libvirt is a launcher for qemu (and I think LXC and maybe something else too). It is convenient. Unless you're doing something funny, there is little reason not to use it on top of qemu.
| Quote: | | 2) do you maybe have some tips regarding performance/security/setup/user-interface tuning of Qemu and related options? |
Virt-manager provides both, user and management inerfaces for qemu VMs 
This said, there's nothing inherently wrong with DIY launchers for your VMs. If you like it raw, go ahead and use it raw.
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NichtDerHans
Apprentice
Joined: 27 Jan 2023
Posts: 192
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| Posted: Thu Mar 06, 2025 11:40 am Post subject: |
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| Virt-Manger <3 |
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NeddySeagoon
Administrator
Joined: 05 Jul 2003
Posts: 54972
Location: 56N 3W
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| Posted: Thu Mar 06, 2025 11:42 am Post subject: |
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carcajou,
What szatox said but libvirt cannot do it all.
I had to use virt-sh to add IPv6 to my virtbr0 interface.
In the early days of KVM support for arm64, it was a while before arm64 came to libvirt.
libvirt makes memory ballooning, moving RAM between VMs, trivial.
I've got lazy. I use libvirt where I can and virt-sh where I must.
Raw qemu is a bit 'hair shirt' but its all there.
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NeddySeagoon
Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail. |
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Anon-E-moose
Watchman
Joined: 23 May 2008
Posts: 6236
Location: Dallas area
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| Posted: Thu Mar 06, 2025 11:56 am Post subject: |
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I always use qemu cmdline.
There is a bit of a learning curve when using cmdline,
but once you know the parameters to use, it's easy to slap it into a shell script (or a bash alias *lol*).
All the vm managers do is pick a common subset of all qemu parms to expose to the user.
It's convenient, but you do give up some control.
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