Re: [RFC] Unify KVM kernel-space and user-space code into a singleproject

From: Avi Kivity
Date: Mon Mar 22 2010 - 02:38:17 EST


On 03/21/2010 10:37 PM, Ingo Molnar wrote:

That includes the guest kernel. If you can deploy a new kernel in the
guest, presumably you can deploy a userspace package.
Note that with perf we can instrument the guest with zero guest-kernel
modifications as well.

We try to reduce the guest impact to a bare minimum, as the difficulties in
deployment are function of the cross section surface to the guest.

Also, note that the kernel is special with regards to instrumentation: since
this is the kernel project, we are doing kernel space changes, as we are doing
them _anyway_. So adding symbol resolution capabilities would be a minimal
addition to that - while adding a while new guest package for the demon would
significantly increase the cross section surface.

It's true that for us, changing the kernel is easier than changing the rest of the guest. IMO we should still resist the temptation to go the easy path and do the right thing (I understand we disagree about what the right thing is).

--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.

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