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This file describes the floppy driver.

FAQ list:

=========

 A FAQ list may be found in the fdutils package (see below), and also

at .

LILO configuration options (Thinkpad users, read this)

======================================================

 The floppy driver is configured using the 'floppy=' option in

lilo. This option can be typed at the boot prompt, or entered in the

lilo configuration file.

 Example: If your kernel is called linux-2.6.9, type the following line

at 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 description

of linux-2.6.9:

 append = "floppy=thinkpad"

 Several floppy related options may be given, example:

 linux-2.6.9 floppy=daring floppy=two_fdc

 append = "floppy=daring floppy=two_fdc"

 If you give options both in the lilo config file and on the boot

prompt, the option strings of both places are concatenated, the boot

prompt options coming last. That's why there are also options to

restore the default behavior.

Module configuration options

============================

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

modprobe floppy 

Example:

 modprobe floppy omnibook messages

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

you can put:

 options floppy omnibook messages

in /etc/modprobe.conf.

 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 on

        certain controllers. This may speed up certain operations.

 floppy=0,daring

        Tells the floppy driver that your floppy controller should be used

        with caution.

 floppy=one_fdc

        Tells the floppy driver that you have only one floppy controller.

        (default)

 floppy=two_fdc

 floppy=
,two_fdc

        Tells the floppy driver that you have two floppy controllers.

        The second floppy controller is assumed to be at 
.

        This option is not needed if the second controller is at address

        0x370, and if you use the 'cmos' option.

 floppy=thinkpad

        Tells the floppy driver that you have a Thinkpad. Thinkpads use an

        inverted 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 workable

        DMA channel for the floppy driver. This option is also useful

        if 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 be

        allocated in virtual memory. However, I advise against this if

        you have an FDC without a FIFO (8272A or 82072). 82072A and

        later are OK. You also need at least a 486 to use nodma.

        If you use nodma mode, I suggest you also set the FIFO

        threshold to 10 or lower, in order to limit the number of data

        transfer interrupts.

        If you have a FIFO-able FDC, the floppy driver automatically

        falls 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 "Bus

        master arbitration error" messages from your Ethernet card (or

        from other devices) while accessing the floppy.

 floppy=usefifo

        Enables the FIFO. (default)

 floppy=,fifo_depth

        Sets the FIFO threshold. This is mostly relevant in DMA

        mode. If this is higher, the floppy driver tolerates more

        interrupt latency, but it triggers more interrupts (i.e. it

        imposes more load on the rest of the system). If this is

        lower, the interrupt latency should be lower too (faster

        processor). The benefit of a lower threshold is less

        interrupts.

        To tune the fifo threshold, switch on over/underrun messages

        using 'floppycontrol --messages'. Then access a floppy

        disk. If you get a huge amount of "Over/Underrun - retrying"

        messages, then the fifo threshold is too low. Try with a

        higher value, until you only get an occasional Over/Underrun.

        It is a good idea to compile the floppy driver as a module

        when doing this tuning. Indeed, it allows to try different

        fifo values without rebooting the machine for each test. Note

        that you need to do 'floppycontrol --messages' every time you

        re-insert the module.

        Usually, tuning the fifo threshold should not be needed, as

        the default (0xa) is reasonable.

 floppy=,,cmos

        Sets the CMOS type of  to . This is mandatory if

        you have more than two floppy drives (only two can be

        described in the physical CMOS), or if your BIOS uses

        non-standard CMOS types. The CMOS types are:

                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 was

        initially chosen to represent floppy *tapes*, and 6 for ED drives.

        AMI ignored this, and used 5 for ED drives. That's why the floppy

        driver 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. This

        is needed on IBM L40SX laptops in certain video modes. (There seems

        to be an interaction between video and floppy. The unexpected

        interrupts affect only performance, and can be safely ignored.)

 floppy=broken_dcl

        Don't use the disk change line, but assume that the disk was

        changed whenever the device node is reopened. Needed on some

        boxes where the disk change line is broken or unsupported.

        This should be regarded as a stopgap measure, indeed it makes

        floppy operation less efficient due to unneeded cache

        flushings, and slightly more unreliable. Please verify your

        cable, connection and jumper settings if you have any DCL

        problems. However, some older drives, and also some laptops

        are known not to have a DCL.

 floppy=debug

        Print debugging messages.

 floppy=messages

        Print informational messages for some operations (disk change

        notifications, warnings about over and underruns, and about

        autodetection).

 floppy=silent_dcl_clear

        Uses a less noisy way to clear the disk change line (which

        doesn't involve seeks). Implied by 'daring' option.

 floppy=,irq

        Sets the floppy IRQ to  instead of 6.

 floppy=,dma

        Sets the floppy DMA channel to  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 speed

           in some more extreme cases."

Supporting utilities and additional documentation:

==================================================

 Additional parameters of the floppy driver can be configured at

runtime. Utilities which do this can be found in the fdutils package.

This package also contains a new version of mtools which allows to

access 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:

 http://fdutils.linux.lu

The fdutils releases can be found at:

 http://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, mail

me at Alain.Knaff@poboxes.com . If you post to Usenet, preferably use

comp.os.linux.hardware. As the volume in these groups is rather high,

be sure to include the word "floppy" (or "FLOPPY") in the subject

line.  If the reported problem happens when mounting floppy disks, be

sure 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 

6-3-2000 :      Original Document