Thanks for your kind help / suggestions.
Here is a more verbose version of the compile error output.
paul@linux-jkcx:~/src/openbios-devel> env V=1 make build-verbose Building... make[1]: Entering directory `/home/paul/src/openbios-devel/obj-sparc32' true true gcc -O2 -g -DFCOMPILER -DBOOTSTRAP -DSWAP_ENDIANNESS -DNATIVE_BITWIDTH_EQUALS_HOST_BITWIDTH -Wall -Wredundant-decls -Wshadow -Wpointer-arith -Wstrict-prototypes -Wmissing-declarations -Wundef -Wendif-labels -Wstrict-aliasing -Wwrite-strings -Wmissing-prototypes -Wnested-externs -W -MMD -MP -MT host/kernel/dict.o -MF 'host/kernel/dict.d' -I../include -I../kernel -I../kernel/include -I./target/include -c -o host/kernel/dict.o ../kernel/dict.c gcc -O2 -g -DFCOMPILER -DBOOTSTRAP -DSWAP_ENDIANNESS -DNATIVE_BITWIDTH_EQUALS_HOST_BITWIDTH -Wall -Wredundant-decls -Wshadow -Wpointer-arith -Wstrict-prototypes -Wmissing-declarations -Wundef -Wendif-labels -Wstrict-aliasing -Wwrite-strings -Wmissing-prototypes -Wnested-externs -W -MMD -MP -MT host/kernel/bootstrap.o -MF 'host/kernel/bootstrap.d' -I../include -I../kernel -I../kernel/include -I./target/include -c -o host/kernel/bootstrap.o ../kernel/bootstrap.c In file included from /usr/include/asm/sigcontext.h:5:0, from /usr/include/bits/sigcontext.h:28, from /usr/include/signal.h:339, from ../kernel/bootstrap.c:13: /usr/include/linux/types.h:27:1: error: unknown type name ‘__u16’ /usr/include/linux/types.h:28:1: error: unknown type name ‘__u16’ /usr/include/linux/types.h:29:1: error: unknown type name ‘__u32’ /usr/include/linux/types.h:30:1: error: unknown type name ‘__u32’ /usr/include/linux/types.h:31:1: error: unknown type name ‘__u64’ /usr/include/linux/types.h:32:1: error: unknown type name ‘__u64’ /usr/include/linux/types.h:34:1: error: unknown type name ‘__u16’ /usr/include/linux/types.h:35:1: error: unknown type name ‘__u32’ In file included from /usr/include/bits/sigcontext.h:28:0, from /usr/include/signal.h:339, from ../kernel/bootstrap.c:13: /usr/include/asm/sigcontext.h:24:2: error: unknown type name ‘__u32’ /usr/include/asm/sigcontext.h:25:2: error: unknown type name ‘__u32’ /usr/include/asm/sigcontext.h:28:2: error: unknown type name ‘__u64’ /usr/include/asm/sigcontext.h:33:2: error: unknown type name ‘__u32’ /usr/include/asm/sigcontext.h:38:2: error: unknown type name ‘__u32’ /usr/include/asm/sigcontext.h:191:2: error: unknown type name ‘__u64’ /usr/include/asm/sigcontext.h:192:2: error: unknown type name ‘__u64’ /usr/include/asm/sigcontext.h:193:2: error: unknown type name ‘__u64’ /usr/include/asm/sigcontext.h:198:2: error: unknown type name ‘__u32’ make[1]: *** [host/kernel/bootstrap.o] Error 1 make[1]: Leaving directory `/home/paul/src/openbios-devel/obj-sparc32' make: *** [build-verbose] Error 1