Documentation/floppy.txt

   1 This file describes the floppy driver.
   2
   3 FAQ list:
   4 =========
   5
   6  A FAQ list may be found in the fdutils package (see below), and also
   7 at http://fdutils.linux.lu/FAQ.html
   8
   9
  10 LILO configuration options (Thinkpad users, read this)
  11 ======================================================
  12
  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
  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):
  19
  20  linux-2.6.9 floppy=thinkpad
  21
  22 You may also enter the following line in /etc/lilo.conf, in the description
  23 of 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
  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.
  36
  37
  38 Module configuration options
  39 ============================
  40
  41  If you use the floppy driver as a module, use the following syntax:
  42 modprobe floppy <options>
  43
  44 Example:
  45  modprobe floppy omnibook messages
  46
  47  If you need certain options enabled every time you load the floppy driver,
  48 you can put:
  49
  50  options floppy omnibook messages
  51
  52 in /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
 208 Supporting utilities and additional documentation:
 209 ==================================================
 210
 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.
 216
 217 The latest version can be found at fdutils homepage:
 218  http://fdutils.linux.lu
 219
 220 The fdutils-5.4 release can be found at:
 221  http://fdutils.linux.lu/fdutils-5.4.src.tar.gz
 222  http://www.tux.org/pub/knaff/fdutils/fdutils-5.4.src.tar.gz
 223  ftp://metalab.unc.edu/pub/Linux/utils/disk-management/fdutils-5.4.src.tar.gz
 224
 225 Reporting problems about the floppy driver
 226 ==========================================
 227
 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.
 234
 235  Be sure to read the FAQ before mailing/posting any bug reports!
 236
 237  Alain
 238
 239 Changelog
 240 =========
 241
 242 10-30-2004 :    Cleanup, updating, add reference to module configuration.
 243                 James Nelson <james4765@gmail.com>
 244
 245 6-3-2000 :      Original Document