Why do some net drivers require __OPTIMIZE__?

[Alex Bennee <alex@braddahead.com>]

Hi,

I've been doing a bring up on an embedded kernel and to prevent gdb
making me go google eyed I notched the optimization level down to -O0
for the time being. This broke the natsemi network driver and I noticed
this stanza appears in a few places:

#if !defined(__OPTIMIZE__)
#warning  You must compile this file with the correct options!
#warning  See the last lines of the source file.
#error You must compile this driver with "-O".
#endif

Despite the comments I couldn't see an explanation at the bottom of the
source file and a quick google showed a few patches where this was
removed but no explanation.

Does anybody know the history behind those lines? Do they serve any
purpose now or in the past? Should I be nervous about compiling the
kernel at a *lower* than normal optimization level? After all
optimizations are generally processor specific and shouldn't affect the
meaning of the C.

-- 
Alex Bennee
Senior Hacker, Braddahead Ltd
The above is probably my personal opinion and may not be that of my
employer