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

[Muli Ben-Yehuda <mulix@xxxxxxxxx>]

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.

Cheers,
Muli
-- 
Muli Ben-Yehuda
http://www.mulix.org | http://mulix.livejournal.com/


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