Documentation/blockdev/floppy.txt - maze/linux - Git at Google

 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 <options>

 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 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
	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 <options>

	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 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