Re: [Valgrind-users] cachegrind on a kernel driver

[Josef W. <Jos...@gm...>]

On Friday 13 October 2006 00:46, Nicholas Nethercote wrote:
> On Thu, 12 Oct 2006, Jim Cromie wrote:
> 
> > Are UML or Xen my best bet for getting some cachegrind data on a kernel
> > driver ?
> > or is there another way I havent thought of ?
> 
> I'm not aware of any easy solution.  I don't think anyone has ever really 
> got UML and Valgrind working together properly.  I've heard that some kernel 
> developers test with Valgrind by pulling out large chunks of kernel code 
> into user-space test harnesses.

Seems to be the best route.

Xen is out of question, as guests directly run on the Xen hypervisor,
and their is no way to control/observe such a guest from a user
process inside of another guest (even from domain 0).

Using VMWare could be more promising, as this is a hosted VM, ie. a
real linux user level process. However, VMWare obviously uses similar
code rewriting/JIT techniques as Valgrind itself (ie. similar complex
as running Valgrind self-hosting); additional, VMWare is a binary blob.
And to get useful profiling results out of it, there would need to
be some debug info redirection to make VMWares JITter transparently
- so probably also a no-go.

Josef

PS: VG client requests to provide debug info redirection for
post processing would be interesting: Think about a Java VM, and
cachegrind directly could annotate Java code.