[Qemu-devel] fdc: refactor device creation causes guest kernel panic

[Stefan Hajnoczi]

The following kernel panic occurs when the RHEL6 installer starts on
qemu.git/master:

BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [<ffffffffa0062ceb>] floppy_ready+0xfb/0x730 [floppy]

For full details see http://pastebin.com/SYE5A6LA.

git-bisect revealed that the following commit causes this panic:

commit 63ffb564dca94f8bda01ed6d209784104630a4d2
Author: Blue Swirl <address@hidden>
Date:   Sat Feb 5 16:32:23 2011 +0000

    fdc: refactor device creation

    Turn fdc_init_isa into an inline function.

    Get floppy geometry directly from the drives.

    Don't expose FDCtrl.

    Signed-off-by: Blue Swirl <address@hidden>

The CMOS value at 0x10 has changed from 0x00 to 0x40 but I have not
located the root cause of the problem.

Blue Swirl: Any thoughts on this bug?

Stefan