[Buildroot] external toolchain --sysroot

[Hamish Moffatt]

Hi Thomas,

Firstly:

The external toolchain --sysroot change in CFLAGS has broken my builds.
(I only just merged into into my tree and tried it, so sorry for the
delayed feedback).

configure scripts are failing to compile any test program, with the
error:

configure:2909: checking for C compiler default output file name
configure:2936: /home/hamish/work/xyz/buildroot/build_armeb/staging_dir/usr/bin/armeb-linux-uclibcgnu-gcc -Os  -I/home/hamish/work/xyz/buildroot/build_armeb/staging_dir/include -I/home/hamish/work/xyz/buildroot/build_armeb/staging_dir/usr/include -I/home/hamish/work/xyz/buildroot/build_armeb/staging_dir/usr/armeb-linux-uclibcgnu/include --sysroot /home/hamish/work/xyz/buildroot/build_armeb/staging_dir/ -Os  -I/home/hamish/work/xyz/buildroot/build_armeb/staging_dir/include -I/home/hamish/work/xyz/buildroot/build_armeb/staging_dir/usr/include -I/home/hamish/work/xyz/buildroot/build_armeb/staging_dir/usr/armeb-linux-uclibcgnu/include --sysroot /home/hamish/work/xyz/buildroot/build_armeb/staging_dir/  -L/home/hamish/work/xyz/buildroot/build_armeb/staging_dir/lib -L/home/hamish/work/xyz/buildroot/build_armeb/staging_dir/usr/lib conftest.c  >&5
/home/hamish/work/xyz/buildroot/build_armeb/staging_dir/usr/bin/armeb-linux-uclibcgnu-ld: cannot find /home/hamish/work/xyz/buildroot/build_armeb/staging_dir/lib/libc.so.0 inside /home/hamish/work/xyz/buildroot/build_armeb/staging_dir/
collect2: ld returned 1 exit status
configure:2939: $? = 1

The library does exist at that location, I guess it doesn't like the
combination of the sysroot and the full path in -L.../lib.

[ 2:49PM] hamish at bach:work/xyz/buildroot $ ls -l /home/hamish/work/xyz/buildroot/build_armeb/staging_dir/lib/libc.so.0 
lrwxrwxrwx 1 hamish hamish 19 2008-11-10 17:15 /home/hamish/work/xyz/buildroot/build_armeb/staging_dir/lib/libc.so.0 -> libuClibc-0.9.29.so

[ 2:54PM] hamish at bach:work/xyz/buildroot $ ls -l /home/hamish/work/xyz/buildroot/build_armeb/staging_dir/lib/libuClibc-0.9.29.so 
-rw-r--r-- 1 hamish hamish 293315 2008-11-10 17:15 /home/hamish/work/xyz/buildroot/build_armeb/staging_dir/lib/libuClibc-0.9.29.so

My gcc is 4.1.2. This might work with newer versions.

I removed the --sysroot in package/Makefile.in and it works again.

What is the purpose of using the --sysroot flag? It's used even if gcc
is configured without it.


Secondly:

The change to toolchain/external-toolchain/ext-tool.mk seems to copy the
sysroot into $(STAGING_DIR) as a side-effect of copying the libs to the
$(TARGET_DIR), not as an explicit dependency.

And in my case, the sysroot IS the $(STAGING_DIR)... but my gcc is not
configured with sysroot so it doesn't do any copying anyway.

I did a fresh checkout of my tree and built the toolchain and then my
board, and it failed as above. gcc has a hardcoded path to libc in it,
so it doesn't expect to get --sysroot as well.

Hamish
-- 
Hamish Moffatt VK3SB <hamish at debian.org> <hamish at cloud.net.au>