FreeBSD/Linux Kernel Cross Reference
sys/Documentation/floppy.txt

     This file describes the floppy driver.
     
     FAQ list:
     =========
     
      A FAQ list may be found in the fdutils package (see below), and also
     at http://fdutils.linux.lu/FAQ.html
     
     
    LILO configuration options (Thinkpad users, read this)
    ======================================================
    
     The floppy driver is configured using the 'floppy=' option in
    lilo. This option can be typed at the boot prompt, or entered in the
    lilo configuration file.
     Example: If your kernel is called linux-2.2.13, type the following line
    at the lilo boot prompt (if you have a thinkpad):
     linux-2.2.13 floppy=thinkpad
    You may also enter the following line in /etc/lilo.conf, in the description
    of linux-2.2.13:
     append = "floppy=thinkpad"
    
     Several floppy related options may be given, example:
     linux-2.2.13 floppy=daring floppy=two_fdc
     append = "floppy=daring floppy=two_fdc"
    
     If you give options both in the lilo config file and on the boot
    prompt, the option strings of both places are concatenated, the boot
    prompt options coming last. That's why there are also options to
    restore the default behavior.
    
     If you use the floppy driver as a module, use the following syntax:
     insmod floppy <options>
    
    Example:
     insmod floppy daring two_fdc
    
     Some versions of insmod are buggy in one way or another. If you have
    any problems (options not being passed correctly, segfaults during
    insmod), first check whether there is a more recent version.
    
     The floppy related options include:
    
     floppy=asus_pci
            Sets the bit mask to allow only units 0 and 1. (default)
    
     floppy=daring
            Tells the floppy driver that you have a well behaved floppy controller.
            This allows more efficient and smoother operation, but may fail on
            certain controllers. This may speed up certain operations.
    
     floppy=0,daring
            Tells the floppy driver that your floppy controller should be used
            with caution.
    
     floppy=one_fdc
            Tells the floppy driver that you have only one floppy controller.
            (default)
    
     floppy=two_fdc
     floppy=<address>,two_fdc
            Tells the floppy driver that you have two floppy controllers.
            The second floppy controller is assumed to be at <address>.
            This option is not needed if the second controller is at address
            0x370, and if you use the 'cmos' option.
    
     floppy=thinkpad
            Tells the floppy driver that you have a Thinkpad. Thinkpads use an
            inverted convention for the disk change line.
    
     floppy=0,thinkpad
            Tells the floppy driver that you don't have a Thinkpad.
    
     floppy=omnibook
     floppy=nodma
            Tells the floppy driver not to use Dma for data transfers.
            This is needed on HP Omnibooks, which don't have a workable
            DMA channel for the floppy driver. This option is also useful
            if you frequently get "Unable to allocate DMA memory" messages.
            Indeed, dma memory needs to be continuous in physical memory,
            and is thus harder to find, whereas non-dma buffers may be
            allocated in virtual memory. However, I advise against this if
            you have an FDC without a FIFO (8272A or 82072). 82072A and
            later are OK. You also need at least a 486 to use nodma.
            If you use nodma mode, I suggest you also set the FIFO
            threshold to 10 or lower, in order to limit the number of data
            transfer interrupts.
    
            If you have a FIFO-able FDC, the floppy driver automatically
            falls back on non DMA mode if no DMA-able memory can be found.
            If you want to avoid this, explicitly ask for 'yesdma'.
    
     floppy=yesdma
            Tells the floppy driver that a workable DMA channel is available.
            (default)
    
     floppy=nofifo
            Disables the FIFO entirely. This is needed if you get "Bus
            master arbitration error" messages from your Ethernet card (or
           from other devices) while accessing the floppy.
   
    floppy=fifo
           Enables the FIFO. (default)
   
    floppy=<threshold>,fifo_depth
           Sets the FIFO threshold. This is mostly relevant in DMA
           mode. If this is higher, the floppy driver tolerates more
           interrupt latency, but it triggers more interrupts (i.e. it
           imposes more load on the rest of the system). If this is
           lower, the interrupt latency should be lower too (faster
           processor). The benefit of a lower threshold is less
           interrupts.
           To tune the fifo threshold, switch on over/underrun messages
           using 'floppycontrol --messages'. Then access a floppy
           disk. If you get a huge amount of "Over/Underrun - retrying"
           messages, then the fifo threshold is too low. Try with a
           higher value, until you only get an occasional Over/Underrun.
           It is a good idea to compile the floppy driver as a module
           when doing this tuning. Indeed, it allows to try different
           fifo values without rebooting the machine for each test. Note
           that you need to do 'floppycontrol --messages' every time you
           re-insert the module.
           Usually, tuning the fifo threshold should not be needed, as
           the default (0xa) is reasonable.
   
    floppy=<drive>,<type>,cmos
           Sets the CMOS type of <drive> to <type>. This is mandatory if
           you have more than two floppy drives (only two can be
           described in the physical CMOS), or if your BIOS uses
           non-standard CMOS types. The CMOS types are:
                   0 - Use the value of the physical CMOS
                   1 - 5 1/4 DD
                   2 - 5 1/4 HD
                   3 - 3 1/2 DD
                   4 - 3 1/2 HD
                   5 - 3 1/2 ED
                   6 - 3 1/2 ED
                  16 - unknown or not installed
           (Note: there are two valid types for ED drives. This is because 5 was
           initially chosen to represent floppy *tapes*, and 6 for ED drives.
           AMI ignored this, and used 5 for ED drives. That's why the floppy
           driver handles both.)
   
    floppy=unexpected_interrupts
           Print a warning message when an unexpected interrupt is received.
           (default)
   
    floppy=no_unexpected_interrupts
    floppy=L40SX
           Don't print a message when an unexpected interrupt is received. This
           is needed on IBM L40SX laptops in certain video modes. (There seems
           to be an interaction between video and floppy. The unexpected
           interrupts affect only performance, and can be safely ignored.)
   
    floppy=broken_dcl
           Don't use the disk change line, but assume that the disk was
           changed whenever the device node is reopened. Needed on some
           boxes where the disk change line is broken or unsupported.
           This should be regarded as a stopgap measure, indeed it makes
           floppy operation less efficient due to unneeded cache
           flushings, and slightly more unreliable. Please verify your
           cable, connection and jumper settings if you have any DCL
           problems. However, some older drives, and also some laptops
           are known not to have a DCL.
   
    floppy=debug
           Print debugging messages.
   
    floppy=messages
           Print informational messages for some operations (disk change
           notifications, warnings about over and underruns, and about
           autodetection).
   
    floppy=silent_dcl_clear
           Uses a less noisy way to clear the disk change line (which
           doesn't involve seeks). Implied by 'daring' option.
   
    floppy=<nr>,irq
           Sets the floppy IRQ to <nr> instead of 6.
   
    floppy=<nr>,dma
           Sets the floppy DMA channel to <nr> instead of 2.
   
    floppy=slow
           Use PS/2 stepping rate:
            " PS/2 floppies have much slower step rates than regular floppies.
              It's been recommended that take about 1/4 of the default speed
              in some more extreme cases."
   
   
   
   Supporting utilities and additional documentation:
   ==================================================
   
    Additional parameters of the floppy driver can be configured at
   runtime. Utilities which do this can be found in the fdutils package.
   This package also contains a new version of mtools which allows to
   access high capacity disks (up to 1992K on a high density 3 1/2 disk!).
   It also contains additional documentation about the floppy driver.
   
   The latest version can be found at fdutils homepage:
    http://fdutils.linux.lu
   
   The fdutils-5.4 release can be found at:
    http://fdutils.linux.lu/fdutils-5.4.src.tar.gz
    http://www.tux.org/pub/knaff/fdutils/fdutils-5.4.src.tar.gz
    ftp://metalab.unc.edu/pub/Linux/utils/disk-management/fdutils-5.4.src.tar.gz
   
   Reporting problems about the floppy driver
   ==========================================
   
    If you have a question or a bug report about the floppy driver, mail
   me at Alain.Knaff@poboxes.com . If you post to Usenet, preferably use
   comp.os.linux.hardware. As the volume in these groups is rather high,
   be sure to include the word "floppy" (or "FLOPPY") in the subject
   line.  If the reported problem happens when mounting floppy disks, be
   sure to mention also the type of the filesystem in the subject line.
   
    Be sure to read the FAQ before mailing/posting any bug reports!
   
    Alain

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