Workaround: compiling GCC 3.0 as a cross-compiler under Linux

[John Zaitseff]

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A number of people have previously queried compiling GCC 3.0 as a 
cross-compiler for embedded systems under Linux.  These people have had 
problems in doing so, with apparently no answers to their queries.

I also have had problems compiling GCC 3.0.2 as a cross-compiler (in my 
case, for arm-elf) under Linux.  I have found a suitable workaround, which 
others having the same problems may like to know.  It probably would be 
good if someone got around to FIXING the problems as well...

1. Download and unpack the GCC sources as per the standard instructions 
(I'll use /usr/local/src/gcc-3.0.2 in this example).  Also create a build 
directory---I'll use /tmp/build/gcc-3.0.2.

2. You need to download and unpack the newlib distribution (currently 
newlib-1.9.0.tar.gz from ftp://sources.redhat.com/pub/newlib) when 
compiling GCC for an embedded system.  The GCC installation documentation 
states that you need "--with-newlib" when configuring GCC, but does NOT 
state that you actually need the newlib distribution present and unpacked, 
at least as far as I can tell!  I'll use /usr/local/src/newlib-1.9.0 in 
this example.

3. Assuming that you have already compiled the binutils package for arm-elf 
and installed it in /usr/local/bin, /usr/local/arm-elf, etc, do the 
following AS ROOT:

    # cd /usr/local/arm-elf
    # mkdir sys-include
    # ln -s sys-include include
    # chmod o+w sys-include

    # cd /usr/local/lib
    # mkdir -p gcc-lib/arm-elf
    # chmod o+w gcc-lib/arm-elf

The reason for the world-writable sys-include directory (a VERY bad idea in 
general) is that GCC's "configure" will copy files from the newlib 
distribution into this directory during configuration.

The reason for the world-writable gcc-lib/arm-elf directory (also a bad 
idea) is that GCC's Makefile will copy files there during "make all".

The reason for the symbolic link /usr/local/arm-elf/include -> sys-include 
is that compiling libiberty (part of GCC) will fail during "make all" if it 
is not present.

4. As an ordinary user, issue the following command (with appropriate 
substitutions for your own set-ups, of course):

    $ cd /tmp/build/gcc-3.0.2
    $ /usr/local/src/gcc-3.0.2/configure --target=arm-elf --with-newlib \
      --with-headers=/usr/local/src/newlib-1.9.0/newlib/libc/include

5. Compile GCC:

    $ make all

6. Now you can install the cross-compiler, and remove the world-writable 
permission from those directories listed above:

    # make install
    # chmod o-w /usr/local/arm-elf/sys-include
    # chmod o-w /usr/local/lib/gcc-lib/arm-elf
    # chown -R root:root /usr/local/arm-elf/sys-include
    # chown -R root:root /usr/local/lib/gcc-lib/arm-elf

7. NOW you can go ahead and compile newlib as per instructions...

This workaround highlights the following bugs:

1. GCC's "configure" expects write-access to system directories (in this 
case /usr/local/arm-elf/sys-include) to copy header files.

2. GCC's Makefile expects write-access to system directories (in this case 
/usr/local/lib/gcc-lib/arm-elf/3.0.2/include) to create "fixed" header 
files.

3. Libiberty's Makefile (in .../libiberty, part of GCC) uses "include" 
instead of "sys-include" when compiling the cross-compiled version of its 
library.  I am not sure if the link created in step 3 needs to be kept 
after GCC's installation.

I hope this helps other people.  Please send any replies directly to my 
e-mail address (J.Zaitseff@zap.org.au) as I am not subscribed to the 
gcc-help mailing list.

Yours truly,

John Zaitseff

- -- 
John Zaitseff                    ,--_|\    The ZAP Group
Phone:  +61 2 9543 6448         /      \   Sydney, Australia
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