MIPS questions

[Joel Sherrill]

Ralf Corsepius wrote:
> 
> Patrick Kelsey wrote:
> >
> > Hello,
> >
> >     We use two mips variants - 64-bit orion processors such as the R4700 and
> > a 32-bit processor based on IDT's RC32300 (a 32-bit mips core with no fpu
> > and a mutt isa: mips2 + non-64-bit mips4 + a few special insns like mad,
> > msub, etc.).  The orion processors are supported directly by the mips64orion
> > targets in the gnu tools and in RTEMS.  To support the 32300-based processor
> > under RTEMS, we added minor patches to the mips64orion cpu-specific files in
> > the distribution.  Originally we used a hacked version of the mips64orion
> > gnu tools, but we are moving to a separate gcc/binutils/newlib target that
> > we have created for the 32300 to circumvent some fundamental problems with
> > the former approach.  So now we have two sets of tools built -
> > mips64orion-rtems-gcc et. al and mips32300-rtems-gcc et. al, with their
> > corresponding newlibs.  The question is what is the best way to add support
> > for building RTEMS with the mips32300 toolset?  The idea is that I would be
> > able to run either of these two commands:
> >
> > bit_rtems mips64orion some_bsp
> > bit_rtems mips32300 some_other_bsp
> >
> > and the configure process would select the appropriate toolset
> > (mips64orion-rtems-* or ) and the appropriate cpu-specific
> > subdirs.  Currently, it seems that the name of the cpu-specifc subdir has to
> > be the same as the cpu name used to form the toolset prefix.
> 
> Almost, things are a little more complicated.

:)  I would like to end up with all mipsXXX-rtems targets being 
variations on the same mips directories.  How to accomplish this
is magic. :)
 
> >  Perhaps there
> > should be separate ways to specify the cpu-specifc subdir name and the tool
> > prefix to accomodate situations like this.
> 
> The subdirs' names are derived by configure scripts calling
> config.sub with the target's canonicalization tripple passed as
> argument to it.
> 
> Manually invoking config.sub:
> sh ./config.sub mips32300-rtems
> mips643200-unknown-rtems
> 
> I.e. config.sub thinks mips32300 is part of a mips643200 cpu family
> => RTEMS configuration would  search for mips643200 subdirs
> internally.

config.sub is broken for this case.  It is this code fragment:

        mips3*-*)
                basic_machine=`echo $basic_machine | sed -e
's/mips3/mips64/'`
                ;;
        mips3*)
                basic_machine=`echo $basic_machine | sed -e
's/mips3/mips64/'`-unknown
                ;;

I saw this by setting -x and trying config.sub.

++ sed s/.*-/-/
+ os=-rtems
++ echo mips32300
++ sed -e s/mips3/mips64/              <=================
+ basic_machine=mips642300-unknown
+ [ x-rtems != x ]
+ vendor=unknown
++ echo mips642300-unknown
++ sed s/unknown/unknown/
+ basic_machine=mips642300-unknown
+ echo mips642300-unknown-rtems
mips642300-unknown-rtems
 
> >  Or am I missing something?
> 
> No, you're basically right, but there is one indirection more than
> you might have expected.
> 
> Ralf

-- 
Joel Sherrill, Ph.D.             Director of Research & Development
joel at OARcorp.com                 On-Line Applications Research
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