[Buildroot] external buildroot toolchain: LD_LIBRARY_PATH needed

On Wed, Aug 24, 2011 at 4:31 PM, Grant Edwards
[off-list ref] wrote:

On 2011-08-24, Thomas De Schampheleire [off-list ref] wrote:

quoted

If I build a buildroot toolchain on machine A, package the
output/host/usr directory and use that as an external toolchain on
machine B, I get errors that cc1 cannot find libmpfr.so.4. The
location of that library is hardcoded in some compiler tools, and
since we are on another machine, the original location does not
exist.

I can work around this by specifying
LD_LIBRARY_PATH=<buildroot>/output/host/opt/ext-toolchain/lib in the
environment, but this is an annoying and not so clean solution.

How is this supposed to work?

Generally, when you run a gcc from somewhere othern than the location
for which it was originally compled you use the --sysroot option on
the compiler command line to tell it where it's now installed.

I don't know if the buildroot toolchain has that enabled or not. ?I
had a lot of problems trying to use a buildroot-generated toolchain as
an external toolchain (this was a year or two back) and switched to
using crosstool-ng to build my toolchains.

The buildroot external-toolchain support uses a 'wrapper' command,
that makes sure that --sysroot, --mtune and the like gets passed to
the compiler.

The sysroot originally is at
output/host/opt/ext-toolchain/powerpc-unknown-linux-uclibc/sysroot
and gets copied to:
/repo/tdescham/buildroot/output/host/usr/powerpc-unknown-linux-uclibc/sysroot

However, the missing library does not seem part of sysroot. It is located at
output/host/opt/ext-toolchain/lib
where libgmp, libmpfr, libexpat etc. reside.

Maybe this wrapper should be adapted as to include the proper LD_LIBRARY_PATH?


How does crosstool-ng handle this fixed-path problem?

Thomas