Note that the Unslung packages build system now builds its own toolchain, so the following information is no longer required, and can be considered as purely historical information.
For NSLU2 Linux development, we are currently using crosstool-0.28-rc35.
Note that crosstool-0.28-rc35 uses kernel 2.4.26 headers, whereas crosstool-0.28-rc37 uses kernel 2.6.8 headers. Neither of these match the kernel that unslung uses, which is 2.4.22. This can cause compilation problems for some Unslung packages, and may also cause run-time problems.
If you have built crosstool according to the instructions previously published here, you may wish to rebuild using the updated instructions - these will explicitly request kernel headers that match what is used by the unslung firmware.
The instructions for building this toolchain can be found here:
Before following the instructions in the above link, make sure you unset LD_LIBRARY_PATH, C_INCLUDE_PATH and CPLUS_INCLUDE_PATH in your environment. Otherwise, you will be unhappy when the build dies partway through. The error message is quite understandable, but once you've unset the variable as directed, the build starts over from scratch.
Also, before you start, make sure you are using a recent stable version of GCC on your build machine. GCC 2.95 is not a recent version :-)
If you have problems (and have followed this exact procedure twice with the same result), then post your complete Linux O/S details, the URLs and md5sums of all the files you downloaded (including the demo-nslu2.sh file you detached from this message), the *exact* commands you typed (yes, every single one of them, copy and paste from your shell window or bash_history), and the error messages (again, copy and paste from your shell window). Also tell us what version of GCC you are using to compile crosstool.
If you have confirmed that a later version of crosstool will build and run correctly, then insert the details here.
20 Oct 2004:
http://kegel.com/crosstool/crosstool-0.28-rc37/buildlogs/0.28 has a compatibility matrix for crosstool.