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freebsd/sys/kern/linker_if.m
Peter Wemm 54823af256 First round implementation of a fine grain enhanced module to module
version dependency system.  This isn't quite finished, but it is at a
useful stage to do a functional checkpoint.

Highlights:
- version and dependency metadata is gathered via linker sets, so things
are handled the same for static kernels and code built to live in a kld.
- The dependencies are at module level (versus at file level).
- Dependencies determine kld symbol search order - this means that you
cannot link against symbols in another file unless you depend on it. This
is so that you cannot accidently unload the target out from underneath
the ones referencing it.
- It is flexible enough that we can put tags in #include files and macros
so that we can get decent hooks for enforcing recompiles on incompatable
ABI changes.  eg: if we change struct proc, we could force a recompile
for all kld's that reference the proc struct.
- Tangled dependency references at boot time are sorted.  Files are
relocated once all their dependencies are already relocated.

Caveats:
- Loader support is incomplete, but has been worked on seperately.
- Actual enforcement of the version number tags is not active yet - just
the module dependencies are live.  The actual structure of versioning
hasn't been agreed on yet. (eg: major.minor, or whatever)
- There is some backwards compatability for old modules without metadata
but I'm not sure how good it is.

This is based on work originally done by Boris Popov (bp@freebsd.org),
but I'm not sure he'd recognize much of it now. Don't blame him. :-)
Also, ideas have been borrowed from Mike Smith.
2000-04-29 13:19:31 +00:00

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Objective-C

#
# Copyright (c) 2000 Doug Rabson
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
# SUCH DAMAGE.
#
# $FreeBSD$
#
#include <sys/linker.h>
INTERFACE linker;
#
# Lookup a symbol in the file's symbol table. If the symbol is not
# found then return ENOENT, otherwise zero.
#
METHOD int lookup_symbol {
linker_file_t file;
const char* name;
c_linker_sym_t* symp;
};
METHOD int symbol_values {
linker_file_t file;
c_linker_sym_t sym;
linker_symval_t* valp;
};
METHOD int search_symbol {
linker_file_t file;
caddr_t value;
c_linker_sym_t* symp;
long* diffp;
};
#
# Unload a file, releasing dependancies and freeing storage.
#
METHOD void unload {
linker_file_t file;
};
#
# Load a file, returning the new linker_file_t in *result. If
# the class does not recognise the file type, zero should be
# returned, without modifying *result. If the file is
# recognised, the file should be loaded, *result set to the new
# file and zero returned. If some other error is detected an
# appropriate errno should be returned.
#
STATICMETHOD int load_file {
linker_class_t cls;
const char* filename;
linker_file_t* result;
};
STATICMETHOD int link_preload {
linker_class_t cls;
const char* filename;
linker_file_t* result;
};
STATICMETHOD int link_preload_finish {
linker_file_t file;
};