j.chitte wrote:
> I have managed to find some information on the subject which seemed
> to indicate fp emulation could be done but I'd need uclibc which in
> itself required a 2.6.x kernel (which is not currently supported by
> TS).
This is not the case. uclibc and glibc both have soft-floats, it's just
a question of how they're handled. You can do software floating point at
the moment, but it will be quite slow - I think that's the intention of
the warning.
> I need to asses how much customisation effort this is going to imply
> and whether I need to find another way to implement what I need
> without fp.
You could also used fixed point integer arithmetic, and go without any
system calls for softfloat - maybe there's even a flag you could pass to
gcc to optimize for fixed-point integer math? It won't be terribly fast
though.
>
> Could someone give me details on what is needed to achieve softfp on
> 7250?
If you're interested in using something new(er) to speed up FP, then you
probably would want to use the EABI. It speeds up soft-floats by a large
factor.
http://www.linuxdevices.com/articles/AT5920399313.html
http://wiki.debian.org/ArmEabiPort
I don't know if anyone has actually gotten an eabi kernel / userland
running on the 7[23]xx boards yet, but I'm currently working on it. I've
built a toolchain as follows:
USE="-*" crossdev -v \
--kernel 2.6.21 \
--libc 2.5-r3 \
--binutils 2.17 \
--gcc 4.2.0 \
--target arm-softfloat-linux-gnueabi
Both the userland and kernel should either both be compiled w/ the EABI
or both not, ... it's possible to have a mixed environment but it would
likely be very complicated.
... I have yet to get a functional kernel out of EABI though :P I seem
to be hitting the 'invalid machine id' problem in the list's archives,
which leads me to believe that the compiler isn't generating the right
endianness or some other register issue. I probably just need to change
my cflags when compiling linux to point specifically to the ep93xx
devices, but haven't touched it for a few days.
Let us know if you make any interesting progress?
~/Chris
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