RTEMS 4.7.99.2 Available -- PowerPC/virtex feedback
Ralf Corsepius
ralf.corsepius at rtems.org
Fri Aug 10 15:34:21 UTC 2007
On Fri, 2007-08-10 at 10:04 -0500, Joel Sherrill wrote:
> Keith Robertson wrote:
> > Joel Sherrill wrote:
> >> Robert S. Grimes wrote:
> >>> gregory.menke at gsfc.nasa.gov wrote:
> >>>
> >>>> You'll have to apply -msoft-float to more than the RTEMS kernel,
> >>>> newlib
> >>>> (being part of the toolchain) needed to be compiled with it as well.
> >>>>
> >>> Does this mean rebuilding gcc? Or can newlib be built separately?
> >>>
> >>> I assume I'll need to reconfigure gcc, right? What switch to I add
> >>> to the configure command?
> >>>
> >> If you are using the RTEMS RPMs or standard configure
> >> command, then you have a lot of multilib variants.
> >>
> >> GCC has some differences for 403, 405, and 405fp.
> >> Is the virtex CPU really a 403 like the CPU_CFLAGS indicates?
> >>
> >> This is the difference from gcc's viewpoint:
> >>
> >> = {{"401", PROCESSOR_PPC403, POWERPC_BASE_MASK | MASK_SOFT_FLOAT},
> >> {"403", PROCESSOR_PPC403,
> >> POWERPC_BASE_MASK | MASK_SOFT_FLOAT | MASK_STRICT_ALIGN},
> >> {"405", PROCESSOR_PPC405,
> >> POWERPC_BASE_MASK | MASK_SOFT_FLOAT | MASK_MULHW |
> >> MASK_DLMZB},
> >> {"405fp", PROCESSOR_PPC405,
> >> POWERPC_BASE_MASK | MASK_MULHW | MASK_DLMZB},
> >> {"440", PROCESSOR_PPC440,
> >> POWERPC_BASE_MASK | MASK_SOFT_FLOAT | MASK_MULHW |
> >> MASK_DLMZB},
> >> {"440fp", PROCESSOR_PPC440,
> >
> > The xilinx virtex 4fx is a ppc405 with no floating point unit. It is
> > definitely not a ppc403.
> >
> Then the custom file needs to change to reflect that and Robert needs
> a fresh RTEMS compile with the new CPU flag to try that. :)
>
> For the libraries, the t-rtems says:
>
> MULTILIB_MATCHES += mcpu?403=mcpu?405
>
> Is this OK?
In my understanding yes.
This lets the mcpu=405 variant use mcpu=403, which should have a
backward compatible ABI.
Problems might arise if compiling rtems with -mcpu=405 and using
-mcpu=403 compiled libs.
So, the solution might be to use -mcpu=403 to compile the BSP.
Ralf
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