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(fdutils.info)Drive type configuration
Drive type configuration and autodetection
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The following options handle the different available drive types,
such as double density vs. high density vs. extra density drives, and 5
1/4 drives vs 3 1/2 drives. Usually the drive type is stored in a
non-volatile memory, called CMOS, under the form of an integer ranging
from 1 to 6.
Different drive types are able to handle and autodetect different
formats (different autodetection lists). They also have different
"native format name". The native format is the "usual" format with the
highest capacity supported by the drive. (For example 720KB on a double
density 3 1/2 drive, and 1.2MB on a high density 5 1/4 drive.)
These settings are only changeable by the super user.
`-c CMOS-TYPE'
`--cmos CMOS-TYPE'
Set the virtual CMOS type of the floppy drive. This is useful if
* the physical CMOS type is wrong (this may happen with BIOSes
which use a non-standard mapping),
* you have more than two drives (the physical CMOS may only
describe up to two drives).
* you have a BIOS that allows swapping drives A: and B: for DOS.
Right now, this CMOS parameter is not used by the kernel, except
for feeding it back to other applications (for instance
`superformat', `floppymeter' or `MAKEFLOPPIES'). It is also
possible to supply a virtual CMOS type with the `cmos' boot option
(Note: Boottime configuration). If possible, I recommend you
use the boot option, rather than `floppycontrol', because the boot
option also sets any parameters derived from the CMOS type, such
as the autodetection list and the native format, whereas
`floppycontrol' does not.
`-A AUTODETECT-SEQ'
`--autodetect AUTODETECT-SEQ'
Set the autodetection sequence (Note: Autodetection) The
autodetection sequence is a comma-separated list of at most eight
format descriptors. Each format descriptor is a format number
optionally followed by the letter `t'. For drive 0, the format
number is the minor device number divided by 4. The autodetection
sequence is used by the driver to find out the format of a newly
inserted disk. The formats are tried one after the other, and the
first matching format is retained. To test the format, the driver
tries to read the first sector on the first track on the first
head when `t' is not given, or the whole first track when `t' is
given. Thus, autodetection cannot detect the number of tracks.
However, this information is contained in the boot sector, which
is now accessible. The boot sector can then be used by mtools to
configure the correct number of tracks.
Example:
7,4,24t,25
means to try out the formats whose minor device numbers are 28
(1.44M), 16 (720KB), 96 (1.76MB), and 100 (1.92MB), in this order.
For the 1.76MB format, try to read the whole track at once.
Reading the whole track at once allows you to distinguish between
two formats which differ only in the number of sectors. (The
format with the most sectors must be tried first.) If you use
mtools(1), you do not need this feature, as mtools can figure out
the number of sectors without any help from the floppy driver, by
looking at the boot sector.
Reading the whole track at once may also speed up the first read
by 200 milliseconds. However, if, on the other hand, you try to
read a disk which has less sectors than the format, you lose some
time.
I suggest that you put the most often used format in the first
place (barring other constraints), as each format that is tried
out takes 400 milliseconds.
`-n NATIVE-FORMAT'
`--native_format NATIVE-FORMAT'
Set the native format of this drive. The native format of a drive
is the highest standard format available for this drive. (Example:
For a 5 1/4 HD drive it is the usual 1200K format.) This is format
is used to make up the format name for the generic device (which
is the name of the native format). This drive name is read back
from the kernel by the `MAKEFLOPPIES' script which uses it to
decide which device nodes to create.
---------- Footnotes ----------
(1) Version 3.0 or higher
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