Re: problems compiling gcc-3.3.5 with newlib-1.12.0

[Dan Kegel <dank at kegel dot com>]

Carlos de wrote:
> > > I'm tring to compile a cross-toolchain for arm-elf on
> > > a IA32 linux box using gcc-3.3.5, binutils-2.15,
> > > newlib-1.12.0 against linux-2.6.9 headers.
>>> [I applied all the patches in crosstool...]
> > It's a good idea to start with clean
> > unpatched sources,
> > and only add patches as you discover you need them.
>
> Agreed. But then why were those patches there in the
> first place? I thought they were to be applied to any
> cross-compiler binutils-2.15.

Read the comments at the top of each patch to see why it's there.
Some are to solve problems building on Solaris,
some are to solve problems building various flavors of Linux,
some are to solve problems building ld with gcc-3.4,
etc.  The comments let you choose intelligently.

> Anyway aside of that thanks Kai for the info on
> copying newlib headers into sys-include. The final gcc
> build went thru without any problems

Yes, Kai has many helpful insights.  One should beware
his bias against building from pristine sources, though;
his first instinct is always "just copy the headers from
the target system", which is fine in many cases (even
required, for the case of closed-source targets) but
which isn't always the best idea for open-source targets.

> However my troubles seem to have increased. It appears
> that what is required is posix thread support (the
> same as that provided by the glibc-linuxthreads
> library ). On checking the configure options for
> newlib-1.13.0  I find that --enable-newlib-multithread
> apparently enables support for multiple theads. Also
> on compiling  newlib with this option i get a
> pthread.h header in $prefix/arm-elf/include which
> (apparently - i havent checked fully) defines the
> thread function headers. However on then trying to
> compile the full gcc (with --enable-threads=posix) [fails.] ...
> I'm still working on this but any inputs here would be
> most welcome as from what info ive found so far
> indicates that newlib does not support pthreads !

I have no experience with newlib, so I can't comment.
(But the --enable-newlib-multithread option seems to be a funny
beast.  I don't know what it does, but judging from what's
in newlib's source tree, I see a copy of linuxthreads,
so I bet pthread support in newlib is a nasty hack
that only works when you're building newlib programs
to run on x86 linux!)

> Also a (hopefully)minor confusion -when
> cross-compiling for target=arm-linux the linux headers
> are required while for arm-elf the linux headers are
> not used. Is this because the target in the first case
> uses glibc which requires linux ? and arm-elf using
> newlib does not require this? I thought any library
> would necessarily require the kernel headers.

The arm-elf target is not a Linux target, so the Linux headers
are not required.  arm-elf is a bare metal target, no OS, I think.
- Dan

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