requires: address@hidden
pc: Add pc-*-2.6 machine classes
Yes, it's been broken for ten years.
No, it's not a CVE.
The problem is that QEMU doesn't have a configuration option for the type
of floppy drive you want. It determines that based on the type of
diskette inserted at boot time.
If you don't insert one, it always chooses a 1.44MB type.
If you want to insert a 2.88MB floppy after boot, you simply cannot.
"Wow, who cares?"
Good question -- Unfortunately, the virtio-win floppy disk images that
Red Hat/Fedora ship require a 2.88MB drive, so if you forgot to insert
them at boot, you'd have to change your VM configuration and try again.
For a one-shot operation, that's kind of obnoxious -- it'd be nice to
allow one to just insert the diskette on-demand.
"OK, What are you changing in this decades-old device?"
(1) Add a new property to allow users to specify what kind of drive they
want without relying on magical guessing behavior.
Choices are: 120, 144, 288, auto, and none.
120, 144 and 288 refer to 1.20MB, 1.44MB, and 2.88MB drives.
auto refers to the auto-detect behavior QEMU currently has.
none ... hides the drive. You probably don't want to use this,
but it's there if you feel like creating a drive you can't use.
(2) Add a new "fallback" property for use with the "auto" drive type
that allows us to specify the backup behavior, too. In most cases
this property won't be needed, but it is provided for allowing
QEMU to be fully backwards compatible.
(3) Add the concept of physical diskette size to QEMU, classifying
120-style diskettes as fundamentally different from 144 and 288
ones.
(4) Revamp the automatic guessing heuristic to understand that
2.88MB style drives can accept 1.44MB diskettes.
(5) Change the automatic fallback type for the automatic guessing
heuristic from 1.44MB to 2.88MB for 2.6 machines and beyond,
leaving 2.5- machines set to default to auto/144.
(6) A lot of code cleanup in general.
"Won't this break everything, you madman?"
No: I tested this in MS-DOS 6.22, Fedora 23 and Windows 8.1. All
seemed perfectly happy with 2.88MB drives as the default for 1.44
or 2.88MB floppy diskette images.
And: Older machine types will happily still default to the 1.44
type just like they used to, so really nothing should change
at all for most guests.
If there ARE any guests affected in 2.6+ machine types, you are
urged to use an explicit drive type that matches your application
if the automatic behavior is unsuitable.
===
v4:
===
Hopefully a more logical patch order with smaller changes.
001/12:[----] [--] 'fdc: move pick_geometry'
002/12:[down] 'fdc: reduce number of pick_geometry arguments'
003/12:[down] 'fdc: add drive type qapi enum'
004/12:[0008] [FC] 'fdc: add disk field'
005/12:[down] 'fdc: Throw an assertion on misconfigured fd_formats table'
006/12:[down] 'fdc: add pick_drive'
007/12:[0018] [FC] 'fdc: Add fallback option'
008/12:[down] 'fdc: add drive type option'
009/12:[----] [-C] 'fdc: add physical disk sizes'
010/12:[0014] [FC] 'fdc: rework pick_geometry'
011/12:[----] [--] 'qtest/fdc: Support for 2.88MB drives'
012/12:[0010] [FC] 'fdc: change auto fallback drive for ISA FDC to 288'
02: Kept both debug printfs in fd_revalidate.
03: New patch, QAPI enumeration change only.
04: Re-ordered FDrive fields
Fallout from 03.
05: New patch.
06: Almost completely re-done.
07: Added media_validated property
Fallout from patch re-ordering.
08: Re-ordered.
10: Changed return type of pick_geometry to int.
Changed one error pathway to abort, as it's not a run-time problem.
12: Rebased on top of current master.
===
v3:
===
001/11:[----] [--] 'fdc: move pick_geometry'
002/11:[----] [--] 'fdc: refactor pick_geometry'
003/11:[----] [--] 'fdc: add disk field'
004/11:[0037] [FC] 'fdc: add default drive type option'
005/11:[down] 'fdc: Add fallback option'
006/11:[----] [-C] 'fdc: do not call revalidate on eject'
007/11:[0030] [FC] 'fdc: implement new drive type property'
008/11:[----] [-C] 'fdc: add physical disk sizes'
009/11:[0018] [FC] 'fdc: rework pick_geometry'
010/11:[----] [--] 'qtest/fdc: Support for 2.88MB drives'
011/11:[down] 'fdc: change auto fallback drive for ISA FDC to 288'
04: Remove typeA/typeB members of FDCtrl. Store e.g. -fdtypeA options
directly into FDCtrl.drives[x].drive instead.
05: Add a new fallback= option that controls fdtype{A,B}=auto behavior.
07: replace get_default_drive_type which is no longer needed
add get_fallback_drive_type.
09: Reworked the auto/fallback section of pick_geometry.
________________________________________________________________________________
For convenience, this branch is available at:
https://github.com/jnsnow/qemu.git branch fdc-default
https://github.com/jnsnow/qemu/tree/fdc-default
This version is tagged fdc-default-v4:
https://github.com/jnsnow/qemu/releases/tag/fdc-default-v4
John Snow (12):
fdc: move pick_geometry
fdc: reduce number of pick_geometry arguments
fdc: add drive type qapi enum
fdc: add disk field
fdc: Throw an assertion on misconfigured fd_formats table
fdc: add pick_drive
fdc: Add fallback option
fdc: add drive type option
fdc: add physical disk sizes
fdc: rework pick_geometry
qtest/fdc: Support for 2.88MB drives
fdc: change auto fallback drive for ISA FDC to 288
hw/block/fdc.c | 315
+++++++++++++++++++++++++++++--------------
hw/core/qdev-properties.c | 11 ++
hw/i386/pc.c | 17 +--
include/hw/block/fdc.h | 9 +-
include/hw/compat.h | 4 +
include/hw/qdev-properties.h | 1 +
qapi/block.json | 16 +++
tests/fdc-test.c | 2 +-
8 files changed, 259 insertions(+), 116 deletions(-)