Genksyms
reads (on standard input) the output from "gcc -E source.c" and
generates a file containing version information.
Depending on the output format indicated by the -k option,
the output will either be written to a .ver file in the named
output directory, or to the standard output.
Genksyms
normally looks for explicit symbol table definitions in the source
file. All definitions and declarations of
typedef, struct, union and enum
will be saved for later expansion.
Every global symbol will also be saved, together with pointers
that will enable a full expansion later on.
When a symbol table is found in the source, the symbol will be
expanded to its full definition, where all structs, unions, enums
and typedefs will be expanded down to their basic part, recursively.
This final string will then be used as input to a CRC algorithm
that will give an integer that will change as soon as any of the
included definitions changes, for this symbol.
The version information in the kernel normally looks like:
symbol_R12345678,
where 12345678 is the hexadecimal representation of the CRC.
OPTIONS
-d, --debug
Output debugging information; repeating this option increases the
verbosity. Debug level 1 generates moderate information about the
actions being taken; debug level 2 enables parser recognition
output; debug level 3 enables lexical analysis output.
-D, --dump
Dump expanded symbol definitions to stderr. For debugging use only.
-h, --help
Display a summary of options and immediately exit.
-kversion, --kernelversion
Select the version of the kernel for which to generate output. Omitting
this option assumes a version below 2.1.0. Versions below 2.1.18
use checksum version 1, and produce their output in the directory given
on the command line. Versions 2.1.18 and above use checksum version 2
and produce their output on stdout.
-pstring, --prefixstring
Prepend the given string to the CRCs generated for all symbols. This is
intended for use with, e.g., SMP kernels, wherein the modules are not
compatible at a level below that described by the data types. This is
primarily caused by inline function expansions in the module code itself.
-q, --quiet
Quiet warnings, i.e. reverse the -w option.
-V, --version
Display the version of genksyms.
-w, --warnings
Enable warnings due to unrecognized syntax and declared but undefined
structures. These warnings are normally suppressed.
The -h option is broken; --help is fine.
genksyms [-V | --version] should display version
information and then exit immediately. Instead, it prints the version
information and behaves as if no options were given.
Although the fix for this bug is trivial, it changes the behaviour of
modutils.
Given the large number of distributions and scripts that run modutils
and expect the current behaviour, any change of behaviour is
unacceptable in 2.4.
Don't bother sending patches for this bug, it will not be fixed in 2.4,
it should be fixed in 2.5.
HISTORY
This versioning concept is a result from discussions, not at least
on the KERNEL-channel, with a lot of people.
