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Annotation of coherent/f/etc/conf/bin/src/assign.h, revision 1.1.1.1

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

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