This file describes the floppy driver.
  
  FAQ list:
  =========
  
   A FAQ list may be found in the fdutils package (see below), and also
  at <http://fdutils.linux.lu/faq.html>.
  
  
  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 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 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=<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 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=<threshold>,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=<drive>,<type>,cmos
  	Sets the CMOS type of <drive> to <type>. 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:
  
  		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 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=<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 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 <james4765@gmail.com>
  
  6-3-2000 :	Original Document