I fixed the following with: (On Ubuntu) sudo apt-get install gcc-multilib paul@jacko:~/gpc1-build$ LANG=C make make[1]: Entering directory '/home/paul/gpc1-build/libiberty' make[2]: Entering directory '/home/paul/gpc1-build/libiberty/testsuite' make[2]: Nothing to be done for 'all'. make[2]: Leaving directory '/home/paul/gpc1-build/libiberty/testsuite' make[1]: Leaving directory '/home/paul/gpc1-build/libiberty' make[1]: Entering directory '/home/paul/gpc1-build/intl' make[1]: Nothing to be done for 'all'. make[1]: Leaving directory '/home/paul/gpc1-build/intl' make[1]: Entering directory '/home/paul/gpc1-build/gcc' cd ../../gpc1/gcc-3.4.6/gcc/p/rts && make -f Makefile.in srcdir=. GCC_VERSION="3.4.6" SHELL="/bin/sh" CFLAGS="-g -O2" PFLAGS="" AR_FLAGS="rc" RTSFLAGS="" GPC_DESTDIR="../.." AR="ar" RANLIB="ranlib" RANLIB_TEST="" generated-files make[2]: Entering directory '/home/paul/gpc1/gcc-3.4.6/gcc/p/rts' make[2]: Nothing to be done for 'generated-files'. make[2]: Leaving directory '/home/paul/gpc1/gcc-3.4.6/gcc/p/rts' cd ../../gpc1/gcc-3.4.6/gcc/p/rts && make -f Makefile.in srcdir=. GCC_VERSION="3.4.6" SHELL="/bin/sh" CFLAGS="-g -O2" PFLAGS="" AR_FLAGS="rc" RTSFLAGS="" GPC_DESTDIR="../.." AR="ar" RANLIB="ranlib" RANLIB_TEST="" generated-files make[2]: Entering directory '/home/paul/gpc1/gcc-3.4.6/gcc/p/rts' make[2]: Nothing to be done for 'generated-files'. make[2]: Leaving directory '/home/paul/gpc1/gcc-3.4.6/gcc/p/rts' cd ../../gpc1/gcc-3.4.6/gcc/p/rts && make -f Makefile.in srcdir=. GCC_VERSION="3.4.6" SHELL="/bin/sh" CFLAGS="-g -O2" PFLAGS="" AR_FLAGS="rc" RTSFLAGS="" GPC_DESTDIR="../.." AR="ar" RANLIB="ranlib" RANLIB_TEST="" generated-files make[2]: Entering directory '/home/paul/gpc1/gcc-3.4.6/gcc/p/rts' make[2]: Nothing to be done for 'generated-files'. make[2]: Leaving directory '/home/paul/gpc1/gcc-3.4.6/gcc/p/rts' cd ../../gpc1/gcc-3.4.6/gcc/p/rts && make -f Makefile.in srcdir=. GCC_VERSION="3.4.6" SHELL="/bin/sh" CFLAGS="-g -O2" PFLAGS="" AR_FLAGS="rc" RTSFLAGS="" GPC_DESTDIR="../.." AR="ar" RANLIB="ranlib" RANLIB_TEST="" generated-files make[2]: Entering directory '/home/paul/gpc1/gcc-3.4.6/gcc/p/rts' make[2]: Nothing to be done for 'generated-files'. make[2]: Leaving directory '/home/paul/gpc1/gcc-3.4.6/gcc/p/rts' cd ../../gpc1/gcc-3.4.6/gcc/p/rts && make -f Makefile.in srcdir=. GCC_VERSION="3.4.6" SHELL="/bin/sh" CFLAGS="-g -O2" PFLAGS="" AR_FLAGS="rc" RTSFLAGS="" GPC_DESTDIR="../.." AR="ar" RANLIB="ranlib" RANLIB_TEST="" generated-files make[2]: Entering directory '/home/paul/gpc1/gcc-3.4.6/gcc/p/rts' make[2]: Nothing to be done for 'generated-files'. make[2]: Leaving directory '/home/paul/gpc1/gcc-3.4.6/gcc/p/rts' make[1]: Circular libgcc.a <- pascal dependency dropped. /home/paul/gpc1-build/gcc/xgcc -B/home/paul/gpc1-build/gcc/ -B/usr/local/x86_64-unknown-linux-gnu/bin/ -B/usr/local/x86_64-unknown-linux-gnu/lib/ -isystem /usr/local/x86_64-unknown-linux-gnu/include -isystem /usr/local/x86_64-unknown-linux-gnu/sys-include -O2 -DIN_GCC    -W -Wall -Wwrite-strings -Wstrict-prototypes -Wmissing-prototypes -Wold-style-definition  -isystem ./include  -I. -I. -I../../gpc1/gcc-3.4.6/gcc -I../../gpc1/gcc-3.4.6/gcc/. -I../../gpc1/gcc-3.4.6/gcc/../include   -g0 -finhibit-size-directive -fno-inline-functions -fno-exceptions -fno-zero-initialized-in-bss -fno-unit-at-a-time -fno-omit-frame-pointer -fno-asynchronous-unwind-tables \    -c ../../gpc1/gcc-3.4.6/gcc/crtstuff.c -DCRT_BEGIN \   -o crtbegin.o In file included from /usr/include/bits/errno.h:26,                  from /usr/include/errno.h:28,                  from ../../gpc1/gcc-3.4.6/gcc/tsystem.h:85,                  from ../../gpc1/gcc-3.4.6/gcc/crtstuff.c:62: /usr/include/linux/errno.h:1:23: asm/errno.h: No such file or directory make[1]: *** [Makefile:1273: crtbegin.o] Error 1 make[1]: Leaving directory '/home/paul/gpc1-build/gcc' make: *** [Makefile:23375: all-gcc] Error 2 paul@jacko:~/gpc1-build$ LANG=C make