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Re: Modularizing net80211 (was: link_set info needed)

On Sat, 28 Apr 2012, Paul Goyette wrote:

For built-in modules, we don't (seem to) have a list of the kernel's program sections, and the module's mod->mod_kobj is NULL. So we can't use the section table to get the start address or size of the section. We do have the start/end symbols that __link_set_foreach() uses to enumerate the members.

For non-built-in modules (whether loaded by boot loader, or later from the file system), we have the section info (it's in the kobj->ko_progtab member), but we don't seem to get the start/end symbols. (Perhaps this could be resolved with some crt*.o type magic, but it appears that the user-land crt stuff is GPL'd so not suitable for kernel use?)

So it seems that we just can't get a single mechanism to work for all modules regardless of source (built-in, boot, or filesys).

I'd still like to find a way forward with this issue.

Since we can differentiate (both at compile time and at run-time) between the two modes (built-in vs loaded), I'd like to propose adding the data to support both modes into the mod_info_t structure:

typedef union {
        struct {                        /* For built-in modules */
                void *list_start;
                void *list_end;
        } func_list;
        const char *section;            /* For loaded modules */
} func_list_t;
typedef struct module {
        u_int                   mod_fbtentries; /* DTrace FBT entrie count */
        int                     mod_flags;
        func_list_t             mod_ctors, mod_dtors;
#define MODFLG_MUST_FORCE       0x01
#define MODFLG_AUTO_LOADED      0x02

} module_t;

Then the MODULE (or MODULE_NEW) macro can intialize the appropriate members of the unions, and the run-time code can find the start and end of the link_set section.


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