It seems most likely that your cross-tools are not set up quite right. Take a failing gcc command and run it with -v -save-temps; the output and the # lines in the foobar.i file ought to show you where the compiler is finding all the files, and if it's getting the wrong errno.h or somesuch. At any rate, you need to include more information (at least the verbatim output from make up to the error) for us to help.