Re: gcc-3.3.2 for Netwinder

["Craig A. Vanderborgh" <craigv at voxware dot com>]

Hi Craig,
> Floating-point support for arm is in flux; a lot of people are
> using soft-float support because it's noticably faster than
> the hardware emulation you're talking about.  I know very
> little about it, so I'm cc'ing the linux-arm-toolchain folks,
> who might know more.
> 
> What are your performance requirements?  Do you need maximal
> speed out of the floating point, or is half fast good enough?
> Are you free to use a more recent gcc?
> Do you need to interwork with software compiled by others?
> - Dan

I have done a lot more digging and have found out what is going on, at
least to some degree.

The netwinder is using "NWFPE", the kernel floating point emulator, to
do the floating point stuff.

When I cross-compile (on x86linux to arm) I can get the correct code
generated if I specify -mhard-float.  But the trouble is, I don't seem
to be able to get the glibc part of the toolchain to compile with this
setting - I see this:

/tmp/ccfcpvcD.s: Assembler messages:
/tmp/ccfcpvcD.s:11: Error: selected processor does not support `rfs r3'
/tmp/ccfcpvcD.s:20: Error: selected processor does not support `wfs r3'

So my problem is really that the crosstool build does not seem to be
able to build glibc with "hard float" so that the linked binary (built
using the cross-compiler) is compatible with the NWFPE libc.so on the
netwinder.

It really does seem to be "just a question of configuration" - for glibc
(getting it built the right way).

Any ideas?

thanks,
craig


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