linux/Documentation/blockdev/floppy.txt
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   1This 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
   7at <http://fdutils.linux.lu/faq.html>.
   8
   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 a configuration file in /etc/modprobe.d/.
  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
 220The 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/
 224
 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
 246
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