Re: [Xen-devel] Recent trace patch not arch-neutral

[Rob Gardner <rob.gardner@xxxxxx>]

Muli Ben-Yehuda wrote:

On Mon, Oct 31, 2005 at 04:26:19PM -0700, Rob Gardner wrote:
  

Rob Gardner wrote:

    

Now, to answer Dan's question- the rdtscll thing is just a time stamp 
counter, expressed in cycles. So on ia64 you could probably replace it 
with an asm statement to read ar.itc to make everything work. We just 
need a little wrapper to do the right thing for each architecture. Now 
Dan, if you were more conveniently located, perhaps we could work 
together and fix this. ;)

      

I imagine we just need something that looks like this in trace.c:

#ifdef x86
      rdtscll(rec->cycles);
#endif
#ifdef IA64
      __asm__ __volatile ("mov %0=ar.itc;;" : "=r"(rec->cycles) :: 
"memory");
#endif
    

Can we please stick with the Linux method and put such arch dependant
ifdefs in headers and not in .c files? e.g. define a cycle_counter()
or somesuch inline function that expands to the right thing for each
arch and put it in asm-arch/... Otherwise, it gets messy very quickly
with the addition of new architectures.

  

Of course it'll be done the right way... That's why I sent out my code "suggestion" along with this comment:

Dan, perhaps you know the nice clean way of doing this sort of thing?

Rob

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