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Linus Torvalds1da177e2005-04-16 15:20:36 -07001This file describes the floppy driver.
2
3FAQ list:
4=========
5
6 A FAQ list may be found in the fdutils package (see below), and also
Randy Dunlap98766fb2005-11-21 21:32:31 -08007at <http://fdutils.linux.lu/faq.html>.
Linus Torvalds1da177e2005-04-16 15:20:36 -07008
9
10LILO configuration options (Thinkpad users, read this)
11======================================================
12
13 The floppy driver is configured using the 'floppy=' option in
14lilo. This option can be typed at the boot prompt, or entered in the
15lilo configuration file.
16
17 Example: If your kernel is called linux-2.6.9, type the following line
18at the lilo boot prompt (if you have a thinkpad):
19
20 linux-2.6.9 floppy=thinkpad
21
22You may also enter the following line in /etc/lilo.conf, in the description
23of linux-2.6.9:
24
25 append = "floppy=thinkpad"
26
27 Several floppy related options may be given, example:
28
29 linux-2.6.9 floppy=daring floppy=two_fdc
30 append = "floppy=daring floppy=two_fdc"
31
32 If you give options both in the lilo config file and on the boot
33prompt, the option strings of both places are concatenated, the boot
34prompt options coming last. That's why there are also options to
35restore the default behavior.
36
37
38Module configuration options
39============================
40
41 If you use the floppy driver as a module, use the following syntax:
42modprobe floppy <options>
43
44Example:
45 modprobe floppy omnibook messages
46
47 If you need certain options enabled every time you load the floppy driver,
48you can put:
49
50 options floppy omnibook messages
51
52in /etc/modprobe.conf.
53
54
55 The floppy driver related options are:
56
57 floppy=asus_pci
58 Sets the bit mask to allow only units 0 and 1. (default)
59
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.
64
65 floppy=0,daring
66 Tells the floppy driver that your floppy controller should be used
67 with caution.
68
69 floppy=one_fdc
70 Tells the floppy driver that you have only one floppy controller.
71 (default)
72
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.
79
80 floppy=thinkpad
81 Tells the floppy driver that you have a Thinkpad. Thinkpads use an
82 inverted convention for the disk change line.
83
84 floppy=0,thinkpad
85 Tells the floppy driver that you don't have a Thinkpad.
86
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.
101
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'.
105
106 floppy=yesdma
107 Tells the floppy driver that a workable DMA channel is available.
108 (default)
109
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.
114
115 floppy=usefifo
116 Enables the FIFO. (default)
117
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.
126
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.
137
138 Usually, tuning the fifo threshold should not be needed, as
139 the default (0xa) is reasonable.
140
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:
146
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
155
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.)
160
161 floppy=unexpected_interrupts
162 Print a warning message when an unexpected interrupt is received.
163 (default)
164
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.)
171
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.
182
183 floppy=debug
184 Print debugging messages.
185
186 floppy=messages
187 Print informational messages for some operations (disk change
188 notifications, warnings about over and underruns, and about
189 autodetection).
190
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.
194
195 floppy=<nr>,irq
196 Sets the floppy IRQ to <nr> instead of 6.
197
198 floppy=<nr>,dma
199 Sets the floppy DMA channel to <nr> instead of 2.
200
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."
206
207
208Supporting utilities and additional documentation:
209==================================================
210
211 Additional parameters of the floppy driver can be configured at
212runtime. Utilities which do this can be found in the fdutils package.
213This package also contains a new version of mtools which allows to
214access high capacity disks (up to 1992K on a high density 3 1/2 disk!).
215It also contains additional documentation about the floppy driver.
216
217The latest version can be found at fdutils homepage:
218 http://fdutils.linux.lu
219
Randy Dunlap98766fb2005-11-21 21:32:31 -0800220The 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/
Linus Torvalds1da177e2005-04-16 15:20:36 -0700224
225Reporting problems about the floppy driver
226==========================================
227
228 If you have a question or a bug report about the floppy driver, mail
229me at Alain.Knaff@poboxes.com . If you post to Usenet, preferably use
230comp.os.linux.hardware. As the volume in these groups is rather high,
231be sure to include the word "floppy" (or "FLOPPY") in the subject
232line. If the reported problem happens when mounting floppy disks, be
233sure to mention also the type of the filesystem in the subject line.
234
235 Be sure to read the FAQ before mailing/posting any bug reports!
236
237 Alain
238
239Changelog
240=========
241
24210-30-2004 : Cleanup, updating, add reference to module configuration.
243 James Nelson <james4765@gmail.com>
244
2456-3-2000 : Original Document