aha154x Device Driver aha154x
Adaptec AHA-154x device driver
The aha154x device driver allows the user to use SCSI interface
devices attached to an Adaptec AHA-154x series host adapter.
The COHERENT aha154x device driver has major number 13. It can
be accessed either as a block-special device or as a character-
special device. The minor number specifies the device and parti-
tion number for disk-type devices, allowing the use of up to 8
SCSI-IDs with up to 4 Logical Unit Numbers (LUNs) per SCSI-ID and
up to four partitions per LUN.
The first open call on a SCSI disk device allocates memory for
the partition table and reads it into memory.
***** Minor Device Numbers *****
The minor device number is decoded as follows:
Bit number: 7 6 5 4 3 2 1 0
Meaning: S I I I L L P P
where S indicates the "special" bit, III indicates a three-bit
field containing the SCSI-ID in the range of 0 through 7, LL in-
dicates a two-bit field containing a LUN in the range of 0
through 3, and PP indicates a two-bit field containing either a
partition number for disk-type devices or a set of special modes
for devices other than disks.
The "special" bit and the partition number interact as follows:
Description S Bit PP Device Type
----------- ----- -- ------ ----
partition a 0 00 /dev/sd?a disk
partition b 0 01 /dev/sd?b disk
partition c 0 10 /dev/sd?c disk
partition d 0 11 /dev/sd?d disk
partition table 1 00 /dev/sd?x disk
no rewind 1 01 /dev/sd?n tape
RESERVED 1 10 --- ----
rewind on close 1 11 /dev/sd? tape
***** Loading The Driver ***** The aha154x loadable device driver
must be loaded a on system which does not have a SCSI hard disk
as the root device via the /etc/drvld command, as follows:
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aha154x Device Driver aha154x
/etc/drvld -r /drv/aha154x
***** Files ***** /dev/sd* -- block-special devices
/dev/rsd* -- character-special devices
***** See Also *****
device drivers, drvld, scsi
***** Notes *****
This release of the aha154x device driver only supports disk-type
devices. A future version of the driver will add support for
tape-type and other devices.
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