[Crash-utility] [RFC] makedumpfile, crash: LZO compression support

[Dave Anderson]

----- Original Message -----

> > This could involve configure.c, but conceivably it could all be
> > done within the Makefile itself.  For example, by entering something
> > like "make compress=lzo2", and then adding this to the Makefile:
> > 
> > ifneq ($(compress),)
> > ifeq ($(compress), lzo2)
> >   LZOFLAG=-DLZO
> >   LZOLIB=-llzo2
> > endif
> > endif
> > 
> > And then the diskdump.c compile line could use ${LZOFLAG}, and the
> > gdb_merge stanza could include ${LZOLIB}.
> > 
> 
> Thanks for accepting the request and for detailed instructions.
> 
> I'll reflect these configuration logic in the next patch.

Actually, thinking more about it, I prefer the second solution:

> On the other hand, the capability of dynamically adding an optional
> library could be a useful feature in general -- not only for LZO 
> compression support, but for other things in the future.
>
> I'm thinking that we could allow the user create an "extralibs" file
> in the top-level directory, and then build_configure() in configure.c
> could read it and dynamically create the LDFLAGS= line in the Makefile.
> Currently LDFLAGS can only be modified manually, but the -static example 
> hasn't worked for a long time, and should be removed.

Then the only issue would be the extra -DLZO to be passed to diskdump.c.
Since any additional library would pretty much always require a conditional
function call or other library-specific reference, a general purpose
"extracflags" file could also be created and read by build_configure(),
and its contents appended to the Makefile's TARGET_CFLAGS line.  

With "extralibs" and "extracfiles", we would have a general-purpose 
solution for adding optional libraries for use by both the top-level
crash sources as well as by extension modules that are built within 
the extensions sub-directory.  It would also negate the need to always
have to enter special "make ..." command every time -- instead just
create the "extralibs" and "extracflags" files, and it gets done 
automatically.

Dave