Return to assign.h CVS log

Up to [MW Coherent from dump] / coherent / b / STREAMS / conf_79

Annotation of coherent/b/STREAMS/conf_79/assign.h, revision 1.1.1.1

1.1       root        1: #ifndef        ASSIGN_H
                      2: #define        ASSIGN_H
                      3: 
                      4: /*
                      5:  *-IMPORTS:
                      6:  *     <sys/compat.h>
                      7:  *             EXTERN_C_BEGIN
                      8:  *             EXTERN_C_END
                      9:  *             PROTO ()
                     10:  *     <kernel/v_types.h>
                     11:  *             major_t
                     12:  *             minor_t
                     13:  */
                     14: 
                     15: #include <sys/compat.h>
                     16: #include <kernel/v_types.h>
                     17: 
                     18: 
                     19: #ifndef        MDEV_T
                     20: #define        MDEV_T
                     21: typedef        struct mdevice  mdev_t;
                     22: #endif
                     23: 
                     24: #ifndef        EXTINFO_T
                     25: #define        EXTINFO_T
                     26: typedef struct extinfo extinfo_t;
                     27: #endif
                     28: 
                     29: 
                     30: /*
                     31:  * Mapping between internal and external numbers is not simple; what makes it
                     32:  * worse is that because there is a single mapping that has to be the same
                     33:  * for both block and character tables, the construction of the bdevsw [] and
                     34:  * cdevsw [] internal tables is constrained. This is only a problem if
                     35:  * multiple external major numbers are allowed, and each device is only
                     36:  * permitted to have a single internal major number. The interpretation of the
                     37:  * 'M' flag in this circumstance is unclear.
                     38:  *
                     39:  * The assign_imajors () code should be able to deal with the most complex
                     40:  * case, which is where multiple external majors may actually be mapped to
                     41:  * multiple internal numbers, thus
                     42:  *
                     43:  *     Block external :            |-----scsi-------|
                     44:  *     Character external:   |--tcp--| |-udp-|  |ttys|
                     45:  *
                     46:  * Might map 'tcp' to internal 0, 'udp' to internal 1, 'ttys' to internal 2,
                     47:  * while 'scsi' would have 0, 1, and 2 as internal major numbers.
                     48:  *
                     49:  * This is all hypothetical at the moment, since multiple majors are new to
                     50:  * Coherent anyway. For simplicity, we may constrain the above to be an error
                     51:  * by requiring unique internal number for each device. However, the machinery
                     52:  * in assign_imajors () will have to be flexible enough to deal with the
                     53:  * above.
                     54:  *
                     55:  * NOTE: The complex model is only applicable if a device does not care what
                     56:  * minor numbers are given to it, since there is a single shared table used
                     57:  * to map a range of external major numbers into a range of internal minor
                     58:  * numbers. Since this table is shared, it constrains even more heavily the
                     59:  * circumstances in which numbers can overlap. Without a flag to detect when
                     60:  * a driver doesn't care about minor numbers, we simply forget about the
                     61:  * complex model.
                     62:  */
                     63: 
                     64: struct extinfo {
                     65:        major_t         ei_nemajors;
                     66:        major_t       * ei_etoimajor;
                     67:        major_t       * ei_minoroffset;
                     68:        int             ei_ncdevs;
                     69:        mdev_t       ** ei_cdevsw;
                     70:        int             ei_nbdevs;
                     71:        mdev_t       ** ei_bdevsw;
                     72:        int             ei_nmodules;
                     73:        mdev_t       ** ei_modules;
                     74: };
                     75: 
                     76: 
                     77: EXTERN_C_BEGIN
                     78: 
                     79: extinfo_t     *        assign_imajors          PROTO ((void));
                     80: 
                     81: EXTERN_C_END
                     82: 
                     83: #endif /* ! defined (ASSIGN_H) */

This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.