Re: [PATCH 5/5 V2] kvm tools: Initialize and use VESA and VNC

Ingo Molnar
2011-05-24T19:04:04Z

* Pekka Enberg <penberg@kernel.org> wrote:

> As for the specific issues you mention, only RCU and locking mechanisms seem
> like something that are not trivial to port (although userspace RCU already
> exists).

Indeed.

> [ Porting lockdep to userspace would be one cool feature, though. ]

Agreed - we already ran into a few locking bugs that were IMO needlessly
difficult to debug - our expectations got spoiled by lockdep i guess! :-)

Porting RCU would also have its distinct advantages in terms of scalability.
While tools/perf/ probably wont need it (all its scalability-relevant code runs
in the kernel), tools/kvm/ definitely looks like a candidate for good
user-space RCU primitives.

> On Tue, May 24, 2011 at 5:37 PM, Avi Kivity <avi@redhat.com> wrote:
> > It's a lot easier to use the native userspace stacks.
>
> We will be using userspace libs where appropriate (like with libvnc).

We are using a fair amount of userspace libraries in perf too: -ldw, -lelf,
-lnewt, -lslang, we used -laudit too for some time.

Thanks,

Ingo