Checking if your kit is complete...
Looks good
Writing Makefile for Linux::NBD
cp lib/Linux/NBD/Client.pm blib/lib/Linux/NBD/Client.pm
cp lib/Linux/NBD.pm blib/lib/Linux/NBD.pm
cp lib/Linux/NBD/Server.pm blib/lib/Linux/NBD/Server.pm
/export/home/cpanrun/build/5.6.1/bin/perl -I/export/home/cpanrun/build/5.6.1/lib/5.6.1/sun4-solaris-thread-multi -I/export/home/cpanrun/build/5.6.1/lib/5.6.1 /export/home/cpanrun/build/5.6.1/lib/5.6.1/ExtUtils/xsubpp  -typemap /export/home/cpanrun/build/5.6.1/lib/5.6.1/ExtUtils/typemap NBD.xs > NBD.xsc && mv NBD.xsc NBD.c
Please specify prototyping behavior for NBD.xs (see perlxs manual)
gcc -c  -DUSE_REENTRANT_API -D_POSIX_PTHREAD_SEMANTICS -D_REENTRANT -fno-strict-aliasing -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -O   -DVERSION=\"0.9\" -DXS_VERSION=\"0.9\" -fPIC -I/export/home/cpanrun/build/5.6.1/lib/5.6.1/sun4-solaris-thread-multi/CORE  NBD.c
NBD.xs:7: endian.h: No such file or directory
NBD.xs:11: byteswap.h: No such file or directory
NBD.xs:15: linux/nbd.h: No such file or directory
make: *** [NBD.o] Error 1