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.

1 files changed, 62 insertions, 0 deletions

diff --git a/sys/sys/module.h b/sys/sys/module.h
index 800f45a..e5f0547 100644
--- a/sys/sys/module.h
+++ b/sys/sys/module.h
@@ -29,6 +29,17 @@
 #ifndef _SYS_MODULE_H_
 #define _SYS_MODULE_H_
 
+/*
+ * Module metadata types
+ */
+#define	MDT_DEPEND	1		/* argument is a module name */
+#define	MDT_MODULE	2		/* module declaration */
+#define	MDT_VERSION	3		/* module version(s) */
+
+#define	MDT_STRUCT_VERSION	1	/* version of metadata structure */
+
+#define	MDT_SETNAME	"modmetadata_set"
+
 typedef enum modeventtype {
     MOD_LOAD,
     MOD_UNLOAD,
@@ -60,12 +71,63 @@ typedef union modspecific {
     u_long	ulongval;
 } modspecific_t;
 
+/*
+ * Module dependency declarartion
+ */
+struct mod_depend {
+    int		md_ver_minimum;
+    int		md_ver_preferred;
+    int		md_ver_maximum;
+};
+
+/*
+ * Module version declaration
+ */
+struct mod_version {
+    int		mv_version;
+};
+
+struct mod_metadata {
+    int		md_version;		/* structure version MDTV_* */
+    int		md_type;		/* type of entry MDT_* */
+    void 	*md_data;		/* specific data */
+    char	*md_cval;		/* common string label */
+};
+
 #ifdef _KERNEL
 
+#include <sys/linker_set.h>
+
+#define MODULE_METADATA(uniquifier, type, data, cval)		\
+    static struct mod_metadata _mod_metadata ## uniquifier = {	\
+	MDT_STRUCT_VERSION,				\
+	type,						\
+	data,						\
+	cval						\
+    };							\
+    DATA_SET(modmetadata_set, _mod_metadata ## uniquifier)
+
+#define MODULE_DEPEND(module, mdepend, vmin, vpref, vmax) \
+    static struct mod_depend _ ##module ## _depend_on_ ## mdepend = {	\
+	vmin,					\
+	vpref,					\
+	vmax					\
+    };						\
+    MODULE_METADATA(_md_ ##module ## _on_ ##mdepend, MDT_DEPEND, \
+	&_ ##module ## _depend_on_ ##mdepend, #mdepend)
+
 #define DECLARE_MODULE(name, data, sub, order) \
+    MODULE_METADATA(_md_ ##name, MDT_MODULE, &data, #name); \
     SYSINIT(name##module, sub, order, module_register_init, &data) \
     struct __hack
 
+#define MODULE_VERSION(module, version) \
+    static struct mod_version _ ## module ## _version = {	\
+	version							\
+    };								\
+    MODULE_METADATA(_ ## module ## _version, MDT_VERSION, 	\
+	& _ ## module ## _version, #module)
+
 void module_register_init(const void *data);
 struct linker_file;
 int module_register(const struct moduledata *data, struct linker_file *lf);