Re: [PATCH] powerpc-eabi board support for Xilinx

[Michael Meissner <meissner at linux dot vnet dot ibm dot com>]

On Wed, Oct 22, 2008 at 10:58:00AM -0700, Michael Eager wrote:
> I've been somewhat annoyed that when gcc is built with
> --target=powerpc-*-eabi, I need to specify a target board with
> -m<board> each time I run gcc to create an executable.  This
> is not the case with --target=powerpc-eabisim, since this
> configuration uses config/rs6000/eabisim.h to overwrite the
> target options in config/rs6000/sysv4.h to force sim to be
> the default.
> 
> The attached patch does two things:  First, it creates a
> --with-board=<board> option which will set the default
> target board for a build with --target=powerpc-*-eabi.  The
> user can still override this with a -m<board> option.  Second,
> it creates -mxilinx, which specifies target options for
> using various Xilinx PowerPC development boards.
> 
> [It's arguable whether any of this should be in sysv4.h,
> or whether there should be different build configurations
> for the various boards, like is done with powerpc-eabisim.
> But this patch maintains compatibility with past builds.]

I'm not the current maintainer of the powerpc stuff, but I did add the
eabisim back in the day when I was the maintainer.  At that time, it was
prevalent to add different board packages via -m<option>.  The problem is it
can take a long time to perculate these changes and the board companies tend to
move much faster, and eventually you wind up with a bunch of -m<option> options
that nobody uses anymore.  The powerpc-eabisim was added primarily to allow the
testsuites to be run without having real hardware.

I thought most of the ppc board packages had moved away from adding -m<option>,
and instead were using specs files or shell script wrappers to add the
particular libraries that were used.  This way they could use an off the shelf
compiler and not have to add libraries.  I must admit to not really knowing
that part of the market these days.

-- 
Michael Meissner, IBM
4 Technology Place Drive, MS 2203A, Westford, MA, 01886, USA
meissner@linux.vnet.ibm.com