Re: Recent trace patch not arch-neutral

[Rob Gardner <rob.gardner@hp.com>]

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Ian Pratt wrote:

>>A recent patch to trace.c uses a call to rdtscll() which is 
>>x86-specific.  Is there an arch-neutral call that can be used 
>>instead?  Or do arch's need to implement this?  (And if the 
>>latter, should we choose a more generic name?)
>>    
>>
>
>The tracebuffer code has always used the cycle counter, so if you've
>previously been compiling it for ia64 it must have previously been using
>some more arch neutral way of accessing it...
>  
>


The deal with this is that the default was always trace=n so the trace 
macros never expanded to anything unless you wanted them to. One of the 
things that Keir did in "cleaning up" my code was to totally eliminate 
all conditional compilation. That's why this problem is suddenly showing 
up on ia64.

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. ;)

Rob


Rob


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