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Documentation / blockdev / floppy.txt

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Based on kernel version 3.13. Page generated on 2014-01-20 22:00 EST.

1	This file describes the floppy driver.
3	FAQ list:
4	=========
6	 A FAQ list may be found in the fdutils package (see below), and also
7	at <http://fdutils.linux.lu/faq.html>.
10	LILO configuration options (Thinkpad users, read this)
11	======================================================
13	 The floppy driver is configured using the 'floppy=' option in
14	lilo. This option can be typed at the boot prompt, or entered in the
15	lilo configuration file.
17	 Example: If your kernel is called linux-2.6.9, type the following line
18	at the lilo boot prompt (if you have a thinkpad):
20	 linux-2.6.9 floppy=thinkpad
22	You may also enter the following line in /etc/lilo.conf, in the description
23	of linux-2.6.9:
25	 append = "floppy=thinkpad"
27	 Several floppy related options may be given, example:
29	 linux-2.6.9 floppy=daring floppy=two_fdc
30	 append = "floppy=daring floppy=two_fdc"
32	 If you give options both in the lilo config file and on the boot
33	prompt, the option strings of both places are concatenated, the boot
34	prompt options coming last. That's why there are also options to
35	restore the default behavior.
38	Module configuration options
39	============================
41	 If you use the floppy driver as a module, use the following syntax:
42	modprobe floppy floppy="<options>"
44	Example:
45	 modprobe floppy floppy="omnibook messages"
47	 If you need certain options enabled every time you load the floppy driver,
48	you can put:
50	 options floppy floppy="omnibook messages"
52	in a configuration file in /etc/modprobe.d/.
55	 The floppy driver related options are:
57	 floppy=asus_pci
58		Sets the bit mask to allow only units 0 and 1. (default)
60	 floppy=daring
61		Tells the floppy driver that you have a well behaved floppy controller.
62		This allows more efficient and smoother operation, but may fail on
63		certain controllers. This may speed up certain operations.
65	 floppy=0,daring
66		Tells the floppy driver that your floppy controller should be used
67		with caution.
69	 floppy=one_fdc
70		Tells the floppy driver that you have only one floppy controller.
71		(default)
73	 floppy=two_fdc
74	 floppy=<address>,two_fdc
75		Tells the floppy driver that you have two floppy controllers.
76		The second floppy controller is assumed to be at <address>.
77		This option is not needed if the second controller is at address
78		0x370, and if you use the 'cmos' option.
80	 floppy=thinkpad
81		Tells the floppy driver that you have a Thinkpad. Thinkpads use an
82		inverted convention for the disk change line.
84	 floppy=0,thinkpad
85		Tells the floppy driver that you don't have a Thinkpad.
87	 floppy=omnibook
88	 floppy=nodma
89		Tells the floppy driver not to use Dma for data transfers.
90		This is needed on HP Omnibooks, which don't have a workable
91		DMA channel for the floppy driver. This option is also useful
92		if you frequently get "Unable to allocate DMA memory" messages.
93		Indeed, dma memory needs to be continuous in physical memory,
94		and is thus harder to find, whereas non-dma buffers may be
95		allocated in virtual memory. However, I advise against this if
96		you have an FDC without a FIFO (8272A or 82072). 82072A and
97		later are OK. You also need at least a 486 to use nodma.
98		If you use nodma mode, I suggest you also set the FIFO
99		threshold to 10 or lower, in order to limit the number of data
100		transfer interrupts.
102		If you have a FIFO-able FDC, the floppy driver automatically
103		falls back on non DMA mode if no DMA-able memory can be found.
104		If you want to avoid this, explicitly ask for 'yesdma'.
106	 floppy=yesdma
107		Tells the floppy driver that a workable DMA channel is available.
108		(default)
110	 floppy=nofifo
111		Disables the FIFO entirely. This is needed if you get "Bus
112		master arbitration error" messages from your Ethernet card (or
113		from other devices) while accessing the floppy.
115	 floppy=usefifo
116		Enables the FIFO. (default)
118	 floppy=<threshold>,fifo_depth
119		Sets the FIFO threshold. This is mostly relevant in DMA
120		mode. If this is higher, the floppy driver tolerates more
121		interrupt latency, but it triggers more interrupts (i.e. it
122		imposes more load on the rest of the system). If this is
123		lower, the interrupt latency should be lower too (faster
124		processor). The benefit of a lower threshold is less
125		interrupts.
127		To tune the fifo threshold, switch on over/underrun messages
128		using 'floppycontrol --messages'. Then access a floppy
129		disk. If you get a huge amount of "Over/Underrun - retrying"
130		messages, then the fifo threshold is too low. Try with a
131		higher value, until you only get an occasional Over/Underrun.
132		It is a good idea to compile the floppy driver as a module
133		when doing this tuning. Indeed, it allows to try different
134		fifo values without rebooting the machine for each test. Note
135		that you need to do 'floppycontrol --messages' every time you
136		re-insert the module.
138		Usually, tuning the fifo threshold should not be needed, as
139		the default (0xa) is reasonable.
141	 floppy=<drive>,<type>,cmos
142		Sets the CMOS type of <drive> to <type>. This is mandatory if
143		you have more than two floppy drives (only two can be
144		described in the physical CMOS), or if your BIOS uses
145		non-standard CMOS types. The CMOS types are:
147			0 - Use the value of the physical CMOS
148			1 - 5 1/4 DD
149			2 - 5 1/4 HD
150			3 - 3 1/2 DD
151			4 - 3 1/2 HD
152			5 - 3 1/2 ED
153			6 - 3 1/2 ED
154		       16 - unknown or not installed
156		(Note: there are two valid types for ED drives. This is because 5 was
157		initially chosen to represent floppy *tapes*, and 6 for ED drives.
158		AMI ignored this, and used 5 for ED drives. That's why the floppy
159		driver handles both.)
161	 floppy=unexpected_interrupts
162		Print a warning message when an unexpected interrupt is received.
163		(default)
165	 floppy=no_unexpected_interrupts
166	 floppy=L40SX
167		Don't print a message when an unexpected interrupt is received. This
168		is needed on IBM L40SX laptops in certain video modes. (There seems
169		to be an interaction between video and floppy. The unexpected
170		interrupts affect only performance, and can be safely ignored.)
172	 floppy=broken_dcl
173		Don't use the disk change line, but assume that the disk was
174		changed whenever the device node is reopened. Needed on some
175		boxes where the disk change line is broken or unsupported.
176		This should be regarded as a stopgap measure, indeed it makes
177		floppy operation less efficient due to unneeded cache
178		flushings, and slightly more unreliable. Please verify your
179		cable, connection and jumper settings if you have any DCL
180		problems. However, some older drives, and also some laptops
181		are known not to have a DCL.
183	 floppy=debug
184		Print debugging messages.
186	 floppy=messages
187		Print informational messages for some operations (disk change
188		notifications, warnings about over and underruns, and about
189		autodetection).
191	 floppy=silent_dcl_clear
192		Uses a less noisy way to clear the disk change line (which
193		doesn't involve seeks). Implied by 'daring' option.
195	 floppy=<nr>,irq
196		Sets the floppy IRQ to <nr> instead of 6.
198	 floppy=<nr>,dma
199		Sets the floppy DMA channel to <nr> instead of 2.
201	 floppy=slow
202		Use PS/2 stepping rate:
203		 " PS/2 floppies have much slower step rates than regular floppies.
204		   It's been recommended that take about 1/4 of the default speed
205		   in some more extreme cases."
208	Supporting utilities and additional documentation:
209	==================================================
211	 Additional parameters of the floppy driver can be configured at
212	runtime. Utilities which do this can be found in the fdutils package.
213	This package also contains a new version of mtools which allows to
214	access high capacity disks (up to 1992K on a high density 3 1/2 disk!).
215	It also contains additional documentation about the floppy driver.
217	The latest version can be found at fdutils homepage:
218	 http://fdutils.linux.lu
220	The fdutils releases can be found at:
221	 http://fdutils.linux.lu/download.html
222	 http://www.tux.org/pub/knaff/fdutils/
223	 ftp://metalab.unc.edu/pub/Linux/utils/disk-management/
225	Reporting problems about the floppy driver
226	==========================================
228	 If you have a question or a bug report about the floppy driver, mail
229	me at Alain.Knaff@poboxes.com . If you post to Usenet, preferably use
230	comp.os.linux.hardware. As the volume in these groups is rather high,
231	be sure to include the word "floppy" (or "FLOPPY") in the subject
232	line.  If the reported problem happens when mounting floppy disks, be
233	sure to mention also the type of the filesystem in the subject line.
235	 Be sure to read the FAQ before mailing/posting any bug reports!
237	 Alain
239	Changelog
240	=========
242	10-30-2004 :	Cleanup, updating, add reference to module configuration.
243			James Nelson <james4765@gmail.com>
245	6-3-2000 :	Original Document
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