FAQ list:¶

A FAQ list may be found in the fdutils package (see below), and alsoat <https://fdutils.linux.lu/faq.html>.

LILO configuration options (Thinkpad users, read this)¶

The floppy driver is configured using the ‘floppy=’ option inlilo. This option can be typed at the boot prompt, or entered in thelilo configuration file.

Example: If your kernel is called linux-2.6.9, type the following lineat the lilo boot prompt (if you have a thinkpad):

linux-2.6.9 floppy=thinkpad

You may also enter the following line in /etc/lilo.conf, in the descriptionof linux-2.6.9:

append = "floppy=thinkpad"

Several floppy related options may be given, example:

linux-2.6.9 floppy=daring floppy=two_fdcappend = "floppy=daring floppy=two_fdc"

If you give options both in the lilo config file and on the bootprompt, the option strings of both places are concatenated, the bootprompt options coming last. That’s why there are also options torestore the default behavior.

Module configuration options¶

If you use the floppy driver as a module, use the following syntax:

modprobe floppy floppy="<options>"

Example:

modprobe floppy floppy="omnibook messages"

If you need certain options enabled every time you load the floppy driver,you can put:

options floppy floppy="omnibook messages"

in a configuration file in /etc/modprobe.d/.

The floppy driver related options are:

floppy=asus_pci

Sets the bit mask to allow only units 0 and 1. (default)

floppy=daring

Tells the floppy driver that you have a well behaved floppy controller.This allows more efficient and smoother operation, but may fail oncertain controllers. This may speed up certain operations.

floppy=0,daring

Tells the floppy driver that your floppy controller should be usedwith caution.

floppy=one_fdc

Tells the floppy driver that you have only one floppy controller.(default)

floppy=two_fdc / floppy=<address>,two_fdc

Tells the floppy driver that you have two floppy controllers.The second floppy controller is assumed to be at <address>.This option is not needed if the second controller is at address0x370, and if you use the ‘cmos’ option.

floppy=thinkpad

Tells the floppy driver that you have a Thinkpad. Thinkpads use aninverted convention for the disk change line.

floppy=0,thinkpad

Tells the floppy driver that you don’t have a Thinkpad.

floppy=omnibook / floppy=nodma

Tells the floppy driver not to use Dma for data transfers.This is needed on HP Omnibooks, which don’t have a workableDMA channel for the floppy driver. This option is also usefulif you frequently get “Unable to allocate DMA memory” messages.Indeed, dma memory needs to be continuous in physical memory,and is thus harder to find, whereas non-dma buffers may beallocated in virtual memory. However, I advise against this ifyou have an FDC without a FIFO (8272A or 82072). 82072A andlater are OK. You also need at least a 486 to use nodma.If you use nodma mode, I suggest you also set the FIFOthreshold to 10 or lower, in order to limit the number of datatransfer interrupts.

If you have a FIFO-able FDC, the floppy driver automaticallyfalls back on non DMA mode if no DMA-able memory can be found.If you want to avoid this, explicitly ask for ‘yesdma’.

floppy=yesdma

Tells the floppy driver that a workable DMA channel is available.(default)

floppy=nofifo

Disables the FIFO entirely. This is needed if you get “Busmaster arbitration error” messages from your Ethernet card (orfrom other devices) while accessing the floppy.

floppy=usefifo

Enables the FIFO. (default)

floppy=<threshold>,fifo_depth

Sets the FIFO threshold. This is mostly relevant in DMAmode. If this is higher, the floppy driver tolerates moreinterrupt latency, but it triggers more interrupts (i.e. itimposes more load on the rest of the system). If this islower, the interrupt latency should be lower too (fasterprocessor). The benefit of a lower threshold is lessinterrupts.

To tune the fifo threshold, switch on over/underrun messagesusing ‘floppycontrol --messages’. Then access a floppydisk. If you get a huge amount of “Over/Underrun - retrying”messages, then the fifo threshold is too low. Try with ahigher value, until you only get an occasional Over/Underrun.It is a good idea to compile the floppy driver as a modulewhen doing this tuning. Indeed, it allows to try differentfifo values without rebooting the machine for each test. Notethat you need to do ‘floppycontrol --messages’ every time youre-insert the module.

Usually, tuning the fifo threshold should not be needed, asthe default (0xa) is reasonable.

floppy=<drive>,<type>,cmos

Sets the CMOS type of <drive> to <type>. This is mandatory ifyou have more than two floppy drives (only two can bedescribed in the physical CMOS), or if your BIOS usesnon-standard CMOS types. The CMOS types are:

0	Use the value of the physical CMOS
1	5 1/4 DD
2	5 1/4 HD
3	3 1/2 DD
4	3 1/2 HD
5	3 1/2 ED
6	3 1/2 ED
16	unknown or not installed

(Note: there are two valid types for ED drives. This is because 5 wasinitially chosen to represent floppytapes, and 6 for ED drives.AMI ignored this, and used 5 for ED drives. That’s why the floppydriver handles both.)

floppy=unexpected_interrupts

Print a warning message when an unexpected interrupt is received.(default)

floppy=no_unexpected_interrupts / floppy=L40SX

Don’t print a message when an unexpected interrupt is received. Thisis needed on IBM L40SX laptops in certain video modes. (There seemsto be an interaction between video and floppy. The unexpectedinterrupts affect only performance, and can be safely ignored.)

floppy=broken_dcl

Don’t use the disk change line, but assume that the disk waschanged whenever the device node is reopened. Needed on someboxes where the disk change line is broken or unsupported.This should be regarded as a stopgap measure, indeed it makesfloppy operation less efficient due to unneeded cacheflushings, and slightly more unreliable. Please verify yourcable, connection and jumper settings if you have any DCLproblems. However, some older drives, and also some laptopsare known not to have a DCL.

floppy=debug

Print debugging messages.

floppy=messages

Print informational messages for some operations (disk changenotifications, warnings about over and underruns, and aboutautodetection).

floppy=silent_dcl_clear

Uses a less noisy way to clear the disk change line (whichdoesn’t involve seeks). Implied by ‘daring’ option.

floppy=<nr>,irq

Sets the floppy IRQ to <nr> instead of 6.

floppy=<nr>,dma

Sets the floppy DMA channel to <nr> instead of 2.

floppy=slow

Use PS/2 stepping rate:

PS/2 floppies have much slower step rates than regular floppies.It's been recommended that take about 1/4 of the default speedin some more extreme cases.

Supporting utilities and additional documentation:¶

Additional parameters of the floppy driver can be configured atruntime. Utilities which do this can be found in the fdutils package.This package also contains a new version of mtools which allows toaccess high capacity disks (up to 1992K on a high density 3 1/2 disk!).It also contains additional documentation about the floppy driver.

The latest version can be found at fdutils homepage:

https://fdutils.linux.lu

The fdutils releases can be found at:

https://fdutils.linux.lu/download.html

http://www.tux.org/pub/knaff/fdutils/

ftp://metalab.unc.edu/pub/Linux/utils/disk-management/

Reporting problems about the floppy driver¶

If you have a question or a bug report about the floppy driver, mailme atAlain.Knaff@poboxes.com . If you post to Usenet, preferably usecomp.os.linux.hardware. As the volume in these groups is rather high,be sure to include the word “floppy” (or “FLOPPY”) in the subjectline. If the reported problem happens when mounting floppy disks, besure to mention also the type of the filesystem in the subject line.

Be sure to read the FAQ before mailing/posting any bug reports!

Alain

Changelog¶

10-30-2004 :

Cleanup, updating, add reference to module configuration.James Nelson <james4765@gmail.com>

6-3-2000 :

Original Document