Re: [Xen-devel] VM System Calls

[Frederic Beck <frederic.beck@xxxxxxxx>]

Well, stupid question in then end. the hypervisor is in xen/ ....

I managed to compile a 3.3.0 hypervisor and make my 2.6.26 kernel
running

fighting now with the tools with compiling errors, but it's advancing :)

thanks
Fred

Le Wed, 26 Nov 2008 11:57:03 +0100,
Frederic Beck <frederic.beck@xxxxxxxx> a Ãcrit :

> Just another quick question.
> 
> After modifying traps.c, to recompile the hypervisor, do I need to
> recompile the whole sources with a make world ? Or is it unnecessary ?
> 
> At the moment I'm running a Debian unstable with the debian packages
> distribution of Xen with hypervisor 3.2 and kernel 2.6.26, and the
> 2.6.18 is not running on my computer.
> 
> The idea would be to compile only the hypervisor, but id did not found
> yet in the documentation how to do it. I'll keep on looking, but is
> you have an idea it would be welcomed :)
> 
> Thanks
> Fred
> 
> Le Wed, 26 Nov 2008 09:50:32 +0100,
> Frederic Beck <frederic.beck@xxxxxxxx> a Ãcrit :
> 
> > Hello
> > 
> > > If you're not averse to modifying the hypervisor, you should be
> > > able to arrange to get what you want.
> > 
> > Not at all :) It's what i was planning to do in the first case.
> > 
> > > For 32-bit guests, we allow the system call to trap directly from
> > > userspace into the PV kernel.  But that's actually an
> > > optimization; it used to be the case that if you disable that
> > > direct-trap, then it will trap to Xen, and Xen will forward it on
> > > to the PV kernel. This will make guest system calls slightly more
> > > expensive, but it will allow you to add the tracing /
> > > instrumentation you want.
> > > 
> > > Yes, it looks like if you comment out the following line in
> > > xen/arch/x86/traps.c:do_set_trap_table():
> > >        if ( cur.vector == 0x80 )
> > >             init_int80_direct_trap(curr);
> > > 
> > > Then all guest traps, including system call, will go through
> > > traps.c:do_guest_trap(), which already traces the trap number.  If
> > > you want more information, you can add more trace info there.
> > 
> > Thanks a lot for your help, i'll give it a try. I just commented out
> > that part, i'll recompile the hypervisor and play with it.
> > 
> > I'll let you know how it works out.
> > 
> > Thanks
> > Fred
> > 
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-devel
> 
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