1 This Readme file describes the floppy driver.
6 A FAQ list may be found in the fdutils package (see below), and also
7 at http://poboxes.com/Alain.Knaff/floppy/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.
16 Example: If your kernel is called linux-pre2.0.9, type the following line
17 at the lilo boot prompt (if you have a thinkpad):
18 linux-pre2.0.9 floppy=thinkpad
19 You may also enter the following line in /etc/lilo.conf, in the description
21 append = "floppy=thinkpad"
23 Several floppy related options may be given, example:
24 linux-pre2.0.9 floppy=daring floppy=two_fdc
25 append = "floppy=daring floppy=two_fdc"
27 If you give options both in the lilo config file and on the boot
28 prompt, the option strings of both places are concatenated, the boot
29 prompt options coming last. That's why there are also options to
30 restore the default behavior.
32 If you use the floppy driver as a module, use the following syntax:
33 insmod floppy 'floppy="<options>"'
36 insmod floppy 'floppy="daring two_fdc"'
38 Note that in this case 'floppy=' should only be typed out once, and
39 not once for each option. You need at least modules-1.3.57 for this
40 method. However, the older environment variable based syntax is still
42 (sh syntax): floppy="daring two_fdc" insmod floppy
43 (csh syntax): setenv floppy "daring two_fdc" ; insmod floppy
45 Some versions of insmod are buggy in one way or another. If you have
46 any problems (options not being passed correctly, segfaults during
47 insmod), first check whether there is a more recent version. If there
48 isn't, use the old method using environment variables.
50 The floppy related options include:
53 Sets the bit mask to allow only units 0 and 1. Obsolete, as
54 this is the default setting anyways
57 Tells the floppy driver that you have a well behaved floppy controller.
58 This allows more efficient and smoother operation, but may fail on
59 certain controllers. This may speed up certain operations.
62 Tells the floppy driver that your floppy controller should be used
66 Tells the floppy driver that you have only floppy controller (default)
69 floppy=<address>,two_fdc
70 Tells the floppy driver that you have two floppy controllers. The
71 second floppy controller is assumed to be at <address>. This
72 option is not needed if the second controller is at address
73 0x370, and if you use the 'cmos' option
76 Tells the floppy driver that you have a Thinkpad. Thinkpads use an
77 inverted convention for the disk change line.
80 Tells the floppy driver that you don't have a Thinkpad.
84 Tells the floppy driver not to use Dma for data transfers.
85 This is needed on HP Omnibooks, which don't have a workable
86 DMA channel for the floppy driver. This option is also useful
87 if you frequently get "Unable to allocate DMA memory" messages.
88 Indeed, dma memory needs to be continuous in physical memory,
89 and is thus harder to find, whereas non-dma buffers may be
90 allocated in virtual memory. However, I advise against this if
91 you have an FDC without a FIFO (8272A or 82072). 82072A and
92 later are OK). You also need at least a 486 to use nodma.
93 If you use nodma mode, I suggest you also set the FIFO
94 threshold to 10 or lower, in order to limit the number of data
97 If you have a FIFO-able FDC, the floppy driver automatically
98 falls back on non DMA mode if no DMA-able memory can be found.
99 If you want to avoid this, explicitely ask for 'yesdma'.
102 Tells the floppy driver that a workable DMA channel is available
106 Disables the FIFO entirely. This is needed if you get "Bus
107 master arbitration error" messages from your Ethernet card (or
108 from other devices) while accessing the floppy.
111 Enables the FIFO (default)
113 floppy=<threshold>,fifo_depth
114 Sets the FIFO threshold. This is mostly relevant in DMA
115 mode. If this is higher, the floppy driver tolerates more
116 interrupt latency, but it triggers more interrupts (i.e. it
117 imposes more load on the rest of the system). If this is
118 lower, the interrupt latency should be lower too (faster
119 processor). The benefit of a lower threshold is less
121 To tune the fifo threshold, switch on over/underrun messages
122 using 'floppycontrol --messages'. Then access a floppy
123 disk. If you get a huge amount of "Over/Underrun - retrying"
124 messages, then the fifo threshold is too low. Try with a
125 higher value, until you only get an occasional Over/Underrun.
126 It is a good idea to compile the floppy driver as a module
127 when doing this tuning. Indeed, it allows to try different
128 fifo values without rebooting the machine for each test. Note
129 that you need to do 'floppycontrol --messages' every time you
130 re-insert the module.
131 Usually, tuning the fifo threshold should not be needed, as
132 the default (0xa) is reasonable.
134 floppy=<drive>,<type>,cmos
135 Sets the CMOS type of <drive> to <type>. This is mandatory if
136 you have more than two floppy drives (only two can be
137 described in the physical CMOS), or if your BIOS uses
138 non-standard CMOS types. The CMOS types are:
139 0 - Use the value of the physical CMOS
146 16 - unknown or not installed
147 (Note: there are two valid types for ED drives. This is because 5 was
148 initially chosen to represent floppy *tapes*, and 6 for ED drives.
149 AMI ignored this, and used 5 for ED drives. That's why the floppy
152 floppy=unexpected_interrupts
153 Print a warning message when an unexpected interrupt is received
156 floppy=no_unexpected_interrupts
158 Don't print a message when an unexpected interrupt is received. This
159 is needed on IBM L40SX laptops in certain video modes. (There seems
160 to be an interaction between video and floppy. The unexpected interrupts
161 only affect performance, and can safely be ignored.)
164 Don't use the disk change line, but assume that the disk was
165 changed whenever the device node is reopened. Needed on some
166 boxes where the disk change line is broken or unsupported.
167 This should be regarded as a stopgap measure, indeed it makes
168 floppy operation less efficient due to unneeded cache
169 flushings, and slightly more unreliable. Please verify your
170 cable, connection and jumper settings if you have any DCL
171 problems. However, some older drives, and also some Laptops
172 are known not to have a DCL.
175 Print debugging messages
178 Print informational messages for some operations (disk change
179 notifications, warnings about over and underruns, and about
182 floppy=silent_dcl_clear
183 Uses a less noisy way to clear the disk change line (which
184 doesn't involve seeks). Implied by daring.
187 Sets the floppy IRQ to <nr> instead of 6
190 Sets the floppy DMA channel to <nr> instead of 2
193 Use PS/2 stepping rate:
194 " PS/2 floppies have much slower step rates than regular floppies.
195 It's been recommended that take about 1/4 of the default speed
196 in some more extreme cases."
200 Supporting utilities and additional documentation:
201 ==================================================
203 Additional parameters of the floppy driver can be configured at run
204 time. Utilities which do this can be found in the fdutils
205 package. This package also contains a new version of mtools which
206 allows to access high capacity disks (up to 1992K on a high density 3
207 1/2 disk!). It also contains additional documentation about the floppy
208 driver. It can be found at:
209 linux.wauug.org:/pub/knaff/fdutils/fdutils-4.3.src.tar.gz
210 sunsite.unc.edu:/pub/Linux/system/Misc/fdutils-4.3.src.tar.gz
211 tsx-11.mit.edu:/pub/linux/sources/sbin/fdutils-4.3.src.tar.gz
213 Alpha patches to these utilities are at:
214 http://www.club.innet.lu/~year3160/fdutils/ALPHA
215 All patches contained in this directory are directly against the base
216 version, i.e. DON'T APPLY THEM ON TOP OF EACH OTHER. Only apply the
219 Reporting problems about the floppy driver
220 ==========================================
222 If you have a question or a bug report about the floppy driver, mail
223 me at Alain.Knaff@poboxes.com . If you post to Usenet, preferably use
224 comp.os.linux.hardware. As the volume in these groups is rather high,
225 be sure to include the word "floppy" (or "FLOPPY") in the subject
226 line. If the reported problem happens when mounting floppy disks, be
227 sure to mention also the type of the filesystem in the subject line.
229 Be sure to read the FAQ before mailing/posting any bug reports!