Re: [Qemu-devel] Thoughts around dtrace linking...

[Lee Essen <lee.essen@nowonline.co.uk>]

On 26/03/2012 11:14, Stefan Hajnoczi wrote:
> On Fri, Mar 23, 2012 at 2:11 PM, Lee Essen<lee.essen@nowonline.co.uk>  wrote:
>>
>> On 23 Mar 2012, at 08:08, Stefan Hajnoczi wrote:
>>
>>> On Thu, Mar 22, 2012 at 05:00:53PM +0000, Lee Essen wrote:
>>>> On 22/03/2012 16:28, Stefan Hajnoczi wrote:
>>>>> On Wed, Mar 21, 2012 at 1:01 PM, Andreas Färber<afaerber@suse.de>    wrote:
>>>>>> Hi,
>>>>>>
>>>>>> Am 21.03.2012 11:45, schrieb Lee Essen:
>>>>>>> I've been trying to find a sensible way to solve the Solaris/Illumos
>>>>>>> dtrace requirement to pass all the objs to the dtrace command so that
>>>>>>> the resultant object file contains all the symbols needed to properly
>>>>>>> link the relevant binary.
>>>>>>>
>>>
>>> If you're able to try out the dependency-based approach that would be a
>>> good starting point.  You may hit a point where it turns out to be too
>>> ugly or complicated - in that case, please post your progress and maybe
>>> someone can help find a way to structure it.  I'm not a make guru but I
>>> can try to give feedback on your patches.
>>>
>>> Stefan
>>>
>>
>> Ok, here's an attempt … it works for me, but I'm not sure how it would work on a different dtrace platform so it will probably need some different guarding … but it shows what it will look like.
>
> The code makes sense to me.  There's a feeling that there must be a
> way to remove the duplication in this approach, but my make foo isn't
> good enough to see how.
>
> As you mentioned, we need a way to distinguish between Solaris DTrace,
> which requires the global .o linking approach, and other
> implementations.  You could use CONFIG_SOLARIS and CONFIG_TRACE_DTRACE
> together to enable the global .o linking.
>

So there is another way that's less duplicative on the non-target stuff. 
If you build all of the objects needed for ALL of the binaries, you 
could then build the dtrace object so that it was a superset, then link 
with that one in all of the final binary linking.

To be honest I think it's probably more confusing to do that, the 
previous approach is more duplicative but easier to follow.

Let me pull a full patch together and see what people think.

Lee.