The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/Documentation/floppy.txt

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    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 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 
  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

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