Review/testing request: changing the detection of data_addr/text_addr

[John Baldwin]

On Wednesday 24 March 2010 3:29:23 pm Nathan Whitehorn wrote:
> We currently detect the offical "text" and "data" addresses for ELF 
> files in kern/imgact_elf.c by the heuristic of calling whichever section 
> contains the executable's entry point the text section and everything 
> else data. In general, both this concept and the very few things that 
> use them are obsolete and rare. The data addresses are, however, used in 
> obreak() to find the current break. On powerpc64, this logic fails, 
> because the entry point points to a function descriptor in the data 
> section, causing sbrk() to fail, which in turn breaks profiling.
> 
> The patch at http://people.freebsd.org/~nwhitehorn/textseg.diff changes 
> this algorithm to make the official text area be the largest executable 
> segment, and all others data. The patch has been tested on sparc64, 
> amd64, powerpc, and (of course) powerpc64, with no evident bad effects.

My only comment is that I would keep the existing language about obreak() as 
it describes multiple data segments, etc.  Instead, I would just use the first 
sentence of your new comment to replace the first paragraph in the old 
comment.

-- 
John Baldwin