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1.1 root 1: notes on mapping Unix disk to DiskObject
2:
3: OBSOLETE as of 25 Oct 91..
4:
5: * block devices map to LogicalDisks. All they can do is open, close,
6: and strategy (readAsync, writeAsync). One per partition.
7:
8: sd0a <==> lsd0a etc.
9:
10: * raw devices other than live partition also map onto LogicalDisks to
11: handle DEV_BSIZE mapping. They can do open, close, read, write, ioctl.
12: One per disk.
13:
14: * live partitions map onto DiskObjects (SCSIDisk, FloppyDisk). They can do
15: read, write (maybe ioctl). One per disk.
16:
17: * some kind of disk with n partitions has:
18: n LDs for block devices (lsd0a, lsd0b, lsd0c)
19: one LD for raw device (rsd0a)
20: one DiskObject subclass for live device (sd0)
21:
22: * Unix level needs to be able to map a dev_t to an id.
23: DiskObject and LogicalDisk should register with Unix-level code via:
24:
25: typedef enum {
26: DISK_TYPE_RAW,
27: DISK_TYPE_BLOCK,
28: DISK_TYPE_LIVE
29: } diskType_t;
30:
31: - (void)registerUnixDisk : (int) Unit
32: partition : (int) partition
33: diskType : (diskType_t)diskType;
34:
35:
36: Unix level will keep a bunch of structs doing this mapping around,
37: probably as an array, not a list, to simplify lookup:
38:
39: one per Unix unit (one for sd0, one for sd1, etc)
40:
41: typedef {
42: id raw_dev_id; // LogicalDisk for raw device
43: id live_part_id; // DiskObject/SCSIDisk (etc) for live partition
44: id block_id[NPART]; // for block devices
45: } struct dev_to_id_map_t;
46:
47: These are allocated statically, and a pointer to the array is kept in
48: each DiskObject's idMapArray instance variable.
49:
50: * SCSIDisk init sequence (# indicates not currently implemented)
51:
52: from somewhere {
53: probe and init SCSIController object;
54: SCSIDisk probe:controllerId {
55: foreach target and lun {
56: if it's a disk we can snag {
57: registerDevice; ==> IODevice
58: registerDisk; ==> DiskObject
59: }
60: }
61: }
62: }
63:
64: DiskObject registerDisk {
65: log raw device info;
66: [registerUnixDisk DISK_TYPE_LIVE];
67: [LogicalDisk probe:self]
68: enable disk insert detection;
69: }
70:
71:
72:
73: Two level config:
74:
75: go thru all dev_type registers; mark as in use those which we have
76: internal drivers for;
77: run Config, give it a chance to hand out dev_types to user-level driver
78: (only dev_types which we don't have internal drivers for will be
79: reported; dev_numbers for devices with internal drivers
80: will be reported as DEV_TYPE_NULL).
81:
82: statically generate array of these at config time:
83:
84: typedef {
85: int (*probe_fcn)(void *regptr);
86: dev_type_t dev_type;
87: } internal_device_driver;
88:
89: note "probe_fcn" might be replaced by some objC enumeration of
90: class names to allow something like [*classname probe]...if not
91: possible, each driver will just have a little C fcn to do this.
92:
93: internal autoconfig {
94: for each device page {
95: get internal_device_driver * for this dev_type;
96: if non-null {
97: dev_port_create() a dev_port;
98: (*probe_fcn)(device_page_ptr, dev_port);
99: }
100: }
101: }
102:
103: in SCSIDiskUnix:
104:
105: internal:
106: sd_probe(device_page_ptr, dev_port)
107: sd_dev_to_id(dev)
108:
109: exported via cdevsw[]:
110: sd_raw_open(dev, flag)
111: sd_raw_close(dev)
112: sd_read(dev, uiop)
113: sd_write(dev, uiop)
114: sd_ioctl(dev, cmd, data, flag)
115:
116: exported via bdevsw[]:
117: sd_block_open(dev, flag)
118: sd_block_close(dev)
119: sd_strategy(bp)
120:
121: misc todo:
122: maybe SCSIController probe: should do probes of all known SCSI devices?
123: iostats needs to work!
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