kern/79944: virtual floppy controller of Virtual PC does not work

[bkoenig at cs.tu-berlin.de]

>Number:         79944
>Category:       kern
>Synopsis:       virtual floppy controller of Virtual PC does not work
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Fri Apr 15 04:10:24 GMT 2005
>Closed-Date:
>Last-Modified:
>Originator:     bkoenig at cs.tu-berlin.de
>Release:        
>Organization:
>Environment:
affects all kernels since Sat Sep 18 04:57:55 2004 UTC (phk's new floppy driver)
>Description:
      The virtual floppy disk controller of Microsoft Virtual PC 2004
does not work. This is not a FreeBSD bug, because the virtual controller
simply does not react on attempted resets. Therefore it might be a bug
of Virtual PC 2004.
>How-To-Repeat:
      Run FreeBSD 5.3-RELEASE or later with Virtual PC and try to use a
floppy disk image as usual. /dev/fd0 is missing. dmesg.boot shows failure with fdc.
>Fix:
      This is not intended as a fix but rather as a hint for users who
just want a working fdc. There is an assertion in fdc_initial_reset in
src/sys/dev/fdc/fdc.c which is true:

  /*
   * Assert a reset to the floppy controller and check that the status
   * register goes to zero.
   */
   fdout_wr(fdc, 0);
   fdout_wr(fdc, 0);
   if (fdsts_rd(fdc) != 0)
       return (ENXIO);

Remove the last two of these lines and build and install a new kernel.

>Release-Note:
>Audit-Trail:
>Unformatted: