Re: [PATCH]: Fix fs modules on sparc64 build with newer gcc

[David Miller]

From: Pavel Roskin <address@hidden>
Date: Sat, 11 Apr 2009 23:53:33 -0400

> On Sat, 2009-04-11 at 01:27 -0700, David Miller wrote:
>> Newer versions of gcc emit references to libgcc internal
>> functions __bswapsi2 and __bswapdi2 when building ufs and
>> some other filesystem modules on sparc64.
>> 
>> Unfortunately older versions of gcc lack these symbols in
>> libgcc so we can't export them universally, we have to check
>> for it using configure link tests.
>> 
>> I commited this under the "trust dave with sparc stuff" rule.
>> Let me know if it that wasn't appropriate in this case :-)
> 
> Actually, changes to configure.ac affect other users as well.  Users of
> other architectures would have to run those checks.

And what kind of problems would that cause?  The symbols would
not be found, the test wouldn't pass, and other platforms don't
use the resulting config.h defines as well.  Only the sparc64
build uses this stuff.

It seems entirely harmless.

> I would try to use weak functions or something like that.  Failing that,
> I would add a check for affected architectures only.  Even if that would
> make the script longer, it would make it clear which architectures need
> the check, which is probably a good idea.

I don't think that would work well, these are symbols we have to
export to modules.

And since as I described above the test and the config.h defines
are totally harmless to other targets, I don't see what the point
is in using a more complicated and indirect implementation.

>> I also rebuild configure when commiting these changes.
> 
> I see that configure and config.h.in we built by different versions of
> autoconf.  That's likely to break.
> 
> I would run autogen.sh and commit all changed files after examining the
> changes.  As a courtesy to others, I install the same version of
> Autoconf that the current configure script was generated with.
> 
> Adding or removing files means that DISTLIST will change.  That should
> be committed as well.

I always check the status of my tree after running autogen.sh so I
would take care of all of these things.