genassym —
emit an assym.h file
genassym |
[-c] [-f]
C compiler invocation |
genassym is a shell script normally used during the
kernel build process to create an assym.h file. This file defines a number of
cpp constants derived from the configuration information
genassym reads from stdin. The generated file is used
by kernel sources written in assembler to gain access to information (e.g.
structure offsets and sizes) normally only known to the C compiler.
Arguments to genassym are usually of the
form ${CC} ${CFLAGS} ${CPPFLAGS} where
${CC} is the C compiler used to compile the kernel,
while ${CFLAGS} and ${CPPFLAGS}
are flag arguments to the C compiler. The script creates a C source file
from its input. Then the C compiler is called according to the script's
arguments to compile this file.
Normally genassym instructs the C compiler
to create an assembler source from the constructed C source. The resulting
file is then processed to extract the information needed to create the
assym.h file. The -c flag instructs
genassym to create slightly different code, generate
an executable from this code and run it. In both cases the assym.h file is
written to stdout. The -f flag instructs
genassym to create forth code.
Either self-explanatory, or generated by one of the programs called from the
script.
The genassym command appeared in NetBSD
1.3 as “genassym.sh” in
/usr/src/sys/kern. It became a userland utility in
NetBSD 4.0.