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

To: Rob Gardner <rob.gardner@xxxxxx>
Subject: Re: [Xen-devel] Recent trace patch not arch-neutral
From: Rob Gardner <rob.gardner@xxxxxx>
Date: Mon, 31 Oct 2005 16:26:19 -0700
Cc: "Magenheimer, Dan \(HP Labs Fort Collins\)" <dan.magenheimer@xxxxxx>, Ian Pratt <m+Ian.Pratt@xxxxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx
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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

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

Rob

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