[dtrace-discuss] dtrace -G (was: Mac OS X 10.5 USDT bug)

[Andreas Färber]

Am 02.07.2008 um 08:22 schrieb James McIlree:

> On Jul 1, 2008, at 10:57 PM, Domas Mituzas wrote:
>
>> 2. Lack of -G makes various software not working. Both MySQL and
>> PECL's dtrace use it, instead of relying on generated .h files.
>
> 	This is the source of some debate between Adam and I :-). We're
> planning to add a -G no-op flag so builds don't fall over, but we have
> no plans to ever support the old DTRACE_PROBE macros.

To add to that debate, I recently added USDT probes to the Mono  
runtime (http://www.mono-project.com). On Mac OS X, this was really  
easy. The dtrace -G for Solaris however does not play nice with GNU  
automake and libtool. Thus, I would rather prefer if Sun would drop  
dtrace -G like Apple did.

But since that is unlikely to happen, it would be nice if Sun/Apple  
could contribute support for dtrace -G to those relatively common open  
source build tools, to facilitate adoption of DTrace. The problem is  
that the .o files to pass to dtrace -G are hidden either behind .lo  
files pointing to PIC and non-PIC .o files, or in .a files hidden  
behind a .la file. Further problems arise from the coexistence of PIC  
and non-PIC versions of the same object file and the usage patterns of  
the .la libraries (object files might be shared by multiple .la  
libraries and/or executables, so the original .o files can't be  
modified or subsequent builds of other components would break for non- 
no-op dtrace -G).

I came up with this dirty hack:
http://anonsvn.mono-project.com/viewcvs/trunk/mono/dtrace-prelink.sh?view=markup

A clean solution is to either drop dtrace -G on every platform or to  
add proper tool support for dtrace -G. I inquired with the libtool  
developers and they would be interested in patches, but I'm still  
pretty lost as to how to go about that myself.

Andreas