KVM on old kernels pre-2.6.28
Some time ago in this list it was mentioned that old kernels pre-2.6.28 don't work well with KVM.
(in particular we have a machine with 2.6.24)
Unfortunately the type of problem was not mentioned in the posts I could find. Is that a performance problem, a stability problem, or a data corruption problem... ?
And I would also like to know if the "problem" can be worked around by installing a new kvm-kmod like 2.6.36.2 or we really need to upgrade the whole kernel to get rid of it.
(I was thinking at installing a new qemu-kvm like the 0.12.5 on that)
Thank you in advance
Quoted 4 lines · Asdo
Some time ago in this list it was mentioned that old kernels pre-2.6.28 don't work well with KVM.
(in particular we have a machine with 2.6.24)
pre 2.6.27 kernels don't have mmu notifiers and thus don't handle overcommit well. No idea if there's anything wrong with 2.6.27 itself.
Quoted 7 lines
Unfortunately the type of problem was not mentioned in the posts I could find. Is that a performance problem, a stability problem, or a data corruption problem... ?
And I would also like to know if the "problem" can be worked around by installing a new kvm-kmod like 2.6.36.2 or we really need to upgrade the whole kernel to get rid of it.
The mmu notifier issue requires 2.6.27 or above. Using kvm-kmod allows you to run a newer kvm on an older kernel, but doesn't fix infrastructure issues like I mentioned.
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(I was thinking at installing a new qemu-kvm like the 0.12.5 on that)
0.12.5 is already old. But why are you running such old and unsupported kernels? I recommend either running a distribution kernel, where someone takes care of bug fixes and security updates, or running one of the stable tree kernels.
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error compiling committee.c: too many arguments to function
Quoted 8 lines · Avi Kivity
Quoted 4 lines · Asdo
Some time ago in this list it was mentioned that old kernels pre-2.6.28 don't work well with KVM.
(in particular we have a machine with 2.6.24)pre 2.6.27 kernels don't have mmu notifiers and thus don't handle overcommit well. No idea if there's anything wrong with 2.6.27 itself.
The KVM code in the 2.6.27 kernel is broken. qemu-kvm emits:
KVM kernel module broken (DESTROY_MEMORY_REGION). Please upgrade to at least kernel 2.6.29 or recent kvm-kmod (see http://sourceforge.net/projects/kvm).
You'll need to use newer kvm-kmod versions.
David
Quoted 11 lines · David Ahern
Quoted 8 lines · Avi Kivity
Quoted 4 lines · Asdo
Some time ago in this list it was mentioned that old kernels pre-2.6.28 don't work well with KVM.
(in particular we have a machine with 2.6.24)pre 2.6.27 kernels don't have mmu notifiers and thus don't handle overcommit well. No idea if there's anything wrong with 2.6.27 itself.
Quoted 7 lines
The KVM code in the 2.6.27 kernel is broken. qemu-kvm emits:
KVM kernel module broken (
DESTROY_MEMORY_REGION). Please upgrade to at least kernel 2.6.29 or recent kvm-kmod (see http://sourceforge.net/projects/kvm).You'll need to use newer kvm-kmod versions.
Ah, but that's not a host kernel issue. So you could have kvm-kmod-2.6.37 atop 2.6.27 (still I wouldn't recommend it).
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error compiling committee.c: too many arguments to function
Quoted 11 lines · Avi Kivity
Quoted 7 lines
The KVM code in the 2.6.27 kernel is broken. qemu-kvm emits:
KVM kernel module broken (
DESTROY_MEMORY_REGION). Please upgrade to at least kernel 2.6.29 or recent kvm-kmod (see http://sourceforge.net/projects/kvm).You'll need to use newer kvm-kmod versions.
Ah, but that's not a host kernel issue. So you could have kvm-kmod-2.6.37 atop 2.6.27 (still I wouldn't recommend it).
I don't understand. If the host kernel is 2.6.27, qemu-kvm complains and refuses to open /dev/kvm. Your options are to upgrade the host kernel or use a newer kvm-kmod version.
Are you saying kvm-kmod-2.6.37 is not advisable on 2.6.27? What about kvm-kmod-2.6.32.27?
David
Quoted 15 lines · David Ahern
Quoted 11 lines · Avi Kivity
Quoted 7 lines
The KVM code in the 2.6.27 kernel is broken. qemu-kvm emits:
KVM kernel module broken (
DESTROY_MEMORY_REGION). Please upgrade to at least kernel 2.6.29 or recent kvm-kmod (see http://sourceforge.net/projects/kvm).You'll need to use newer kvm-kmod versions.
Ah, but that's not a host kernel issue. So you could have kvm-kmod-2.6.37 atop 2.6.27 (still I wouldn't recommend it).
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I don't understand. If the host kernel is 2.6.27, qemu-kvm complains and refuses to open
/dev/kvm. Your options are to upgrade the host kernel or use a newer kvm-kmod version.Are you saying kvm-kmod-2.6.37 is not advisable on 2.6.27? What about kvm-kmod-2.6.32.27?
No, that kvm-kmod-2.6.27, or a pure 2.6.27 isn't good. kvm-kmod-2.6.29+ over 2.6.27+ (for mmu notifiers) or a pure 2.6.29+ setup is fine. If you're careful with overcommit you might get away with a pre 2.6.27 host.
(but take all that with a grain of salt, I haven't run kvm-kmod for a long while apart from the RHEL 5 version, and I won't recommend anything outside a supported distro kernel or an active Linux stable/longterm tree).
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error compiling committee.c: too many arguments to function
Quoted 1 line · Avi Kivity
... Using kvm-kmod allows you to run a newer kvm on an older kernel ...
ok thanks
Regarding this: I can't find the kmod version requirements for every KVM version.
What happens if the kernel module version I'm running is too old for the KVM I'm trying to run? Will it fail at startup giving an error, or I won't be warned and then weird things will happen sometime during runtime? If it's the latter, can I at least be sure that always installing the latest kvm-kmod will not do harm to any KVM, even if the KVM is older?
Thank you
Quoted 7 lines · Asdo
Quoted 1 line · Avi Kivity
... Using kvm-kmod allows you to run a newer kvm on an older kernel ...
ok thanks
Regarding this: I can't find the kmod version requirements for every KVM version.
I don't think there is an exhaustive list.
Quoted 5 lines
What happens if the kernel module version I'm running is too old for the KVM I'm trying to run? Will it fail at startup giving an error, or I won't be warned and then weird things will happen sometime during runtime? If it's the latter, can I at least be sure that always installing the latest kvm-kmod will not do harm to any KVM, even if the KVM is older?
There is no warranty.
Signature · 1 line
error compiling committee.c: too many arguments to function