Re: [PATCH 4 of 4] Add a trace hypercall to allow tracing from dom0 or domU

[George Dunlap <george.dunlap@citrix.com>]

On Mon, 2011-07-18 at 09:56 +0100, Tim Deegan wrote:
> Hi, 
> 
> At 17:38 +0200 on 15 Jul (1310751488), Olaf Hering wrote:
> > diff -r 6e4aef7b5051 -r f72dcd1b8bbd xen/arch/x86/x86_32/entry.S
> > --- a/xen/arch/x86/x86_32/entry.S
> > +++ b/xen/arch/x86/x86_32/entry.S
> > @@ -699,6 +699,7 @@ ENTRY(hypercall_table)
> >          .long do_domctl
> >          .long do_kexec_op
> >          .long do_tmem_op
> > +        .long do_xentrace_op
> >          .rept __HYPERVISOR_arch_0-((.-hypercall_table)/4)
> >          .long do_ni_hypercall
> >          .endr
> > @@ -747,6 +748,7 @@ ENTRY(hypercall_args_table)
> >          .byte 1 /* do_domctl            */
> >          .byte 2 /* do_kexec_op          */
> >          .byte 1 /* do_tmem_op           */
> > +        .byte 0 /* do_xentrace_op       */
> >          .rept __HYPERVISOR_arch_0-(.-hypercall_args_table)
> >          .byte 0 /* do_ni_hypercall      */
> >          .endr
> > diff -r 6e4aef7b5051 -r f72dcd1b8bbd xen/arch/x86/x86_64/entry.S
> > --- a/xen/arch/x86/x86_64/entry.S
> > +++ b/xen/arch/x86/x86_64/entry.S
> > @@ -694,6 +694,7 @@ ENTRY(hypercall_table)
> >          .quad do_domctl
> >          .quad do_kexec_op
> >          .quad do_tmem_op
> > +        .quad do_xentrace_op
> >          .rept __HYPERVISOR_arch_0-((.-hypercall_table)/8)
> >          .quad do_ni_hypercall
> >          .endr
> > @@ -742,6 +743,7 @@ ENTRY(hypercall_args_table)
> >          .byte 1 /* do_domctl            */
> >          .byte 2 /* do_kexec             */
> >          .byte 1 /* do_tmem_op           */
> > +        .byte 0 /* do_xentrace_op       */
> >          .rept __HYPERVISOR_arch_0-(.-hypercall_args_table)
> >          .byte 0 /* do_ni_hypercall      */
> >          .endr
> 
> You need to do the same in x86/x86_64/compat/entry.S for 32-on-64 guests
> to be able to call it too.
> 
> Also, can you add some comments somewhere (say, public/trace.h) to say
> exactly what the new hypercall does and how to use it?  A patch to
> docs/src/interface.tex would be great too, even if the rest of that doc
> is quite out of date. 
> 
> George, is it worth trying to merge this into the existing HVMOP that
> does the same thing?

I'm not sure what you mean by "merging this into the existing HVMOP".
Do you mean just having dom0 (or whoever) call HVMOP_trace instead of
making a separate hypercall?

 -George