Re: glibc for mpc860

Dan Malek wrote:

Brendan Simon wrote:

quoted

... I dowloaded the latest glibc (2.1.1) from a GNU mirror
and it compiled fine with my egcs-1.1.2 powerpc-linux cross-compiler.  I
tried adding the -mcpu=860 option and it barfed.

I still use the old libc-1.99 stuff.  I have not looked into
using the newer glibc2.  I don't use cross compilers because of
problems others have had.  That could be some of the problem
as well.

I just downloaded the tar.gz archive from the LinuxPPC ftp site.  It has the libaries but not the source.  I thought at least
the headers would be in there but it doesn't look like it.
Excuse my ignorance but is the libc-1.99 stuff a GNU product ?

I assume by the statement "I don't use cross compilers" means that you use the native compiler on a LinuxPPC machine (powermac
or something).  This would mean that the instructions generated are for 601, 603 or whatever the default is.  This would surely
cause problems on an MPC860 processor wouln't it ?

quoted

..... I assume that the glibc
developers do not consider targets without a floating point processor as
a non-priority (I wish the MPC860 had an FPU).

It seems anything that is not the latest and fastest silicon is
a non-priority :-).  I had the patches for the libraries in the
past....no one was interested.  If you really need an FPU, you
should probably be using something other than an 8xx.  I have done
lots of cool 8xx applications, mostly communications related.
I have never needed an FPU.

I don't have a NEED for an FPU for most projects but I still wish it was available.  There aren't too many CPUs these days that
don't have one built in (except for 8, 16 and some embedded 32 bit processors).  A lot of software these days assumes that an
FPU is present (eg. glibc by the looks of it).  It would be nice to have an FPU just incase it was useful.  I'm sure it wouldn't
cost Motorola much to put it on.  It's just a wish.  Sigh...  I thought the MPC8260 would have an FPU but it appears not.  Ah
well.

quoted

......It looks like others
have ported/modified some glibc sources to work with the -mcpu=860
option.

You shouldn't have to modify anything in the sources to get it
to compile.  The hardest part is getting the flags in the Makefiles.

I think I used something like "CC=powerpc-linux CFLAGS=-mcpu=860 configure" when I tried compiling glibc.  The -mcpu=860 flag
was present in the commands generated by Make which caused the glibc build to die.  Maybe there is something like -msoft or -nfp
that I can try ?

I attached the single file to be modified for the cache line stuff
in the older glibc-1.99 sources.  You can also remove the floating
point instructions in the set/long jump function, but it is not
necessary.  Those are the only floating point instructions in
the libraries.

I'll have a look.

Thanks,
Brendan Simon.


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