Re: GCC: different OS targets.

[Joel Sherrill <joel.sherrill@OARcorp.com>]

This is technically feasible.  Eric Valette for one has mentioned
using the Linux native compiler to target the i386 embedded.  The key
is being able to override the use of ALL include files and libraries.

You are still responsible for building an OS dependent C Library.  Also
you might run into problems with some of the startup files.



Brendan Simon wrote:
> 
> There seems to be different builds of egcs/gcc for various Operating
> Systems (eg. eCos, RTEMS).  I predominantly use the powerpc-eabi
> target.  I currently use it with No OS (NOS) on some MPC860 boards but
> would like to use an OS.  Both RTEMS and eCos use EABI as well, so the
> same compiler should be useable for GCC targeting RTEMS, eCos and NOS.
> 
> I would like to be able to build gcc _ONCE_ for powerpc-eabi and be able
> to build the RTEMS, eCos (or any other OS) libraries and install them in
> an appropriate place.  This not only saves a lot of disk space but also
> a lot time recompiling for each OS evertime a new version of GCC is
> released (or snapshots).
> 
> I figure that the -m switch might be appropriate for choosing the
> operating system.  Powerpc has a -mads (amongst others) switch which
> links the ads crt0.o file and libads via the specs file.  Does the specs
> file only work with the -m switch all will it work with any other swtich
> ?  The -m switch could be used to select the operating system.  eg. "-m
> ads-rtems" or "-m rtems-ads".  A separate directory for the OS stuff
> would be setup in $prefix$target/$os  (eg. /usr/local/gcc/rtems/include
> and /usr/local/gcc/rtems/lib) or maybe $prefix/$target/os/$os (eg.
> /usr/local/gcc/os/rtems/... or /usr/local/gcc/os/none/...).
> 
> I know this would take some cooperation between the OS vendors that
> support GCC but I believe that it would be worth it.  Please voice your
> opinion if you think this is a good or bad idea.
> 
> Brendan Simon.
> 
> PS. I have used eCos and RTEMS as examples only.  I'm sure there are
> other OSs that use gcc (vxworks) that would benefit from a formal mehod
> of implemting multiple OSs using the one compiler.
> 
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-- 
Joel Sherrill, Ph.D.             Director of Research & Development
joel@OARcorp.com                 On-Line Applications Research
Ask me about RTEMS: a free RTOS  Huntsville AL 35805
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