Re: [PATCH v2 1/3] fdc: Drop deprecated floppy configuration

["Daniel P. Berrangé" <berrange@redhat.com>]

On Thu, Mar 04, 2021 at 05:52:50PM +0100, Peter Krempa wrote:
> On Thu, Mar 04, 2021 at 17:23:05 +0100, Markus Armbruster wrote:
> > Daniel P. Berrangé <berrange@redhat.com> writes:
> > 
> > > On Thu, Mar 04, 2021 at 03:26:55PM +0100, Markus Armbruster wrote:
> > >> Daniel P. Berrangé <berrange@redhat.com> writes:
> > >> 
> > >> > On Thu, Mar 04, 2021 at 11:00:57AM +0100, Markus Armbruster wrote:
> > >> >> Drop the crap deprecated in commit 4a27a638e7 "fdc: Deprecate
> > >> >> configuring floppies with -global isa-fdc" (v5.1.0).
> > >> >> 
> > >> >> Signed-off-by: Markus Armbruster <armbru@redhat.com>
> > >> >> ---
> > >> >>  docs/system/deprecated.rst       |  26 --
> > >> >>  docs/system/removed-features.rst |  26 ++
> > >> >>  hw/block/fdc.c                   |  54 +--
> > >> >>  tests/qemu-iotests/172           |  31 +-
> > >> >>  tests/qemu-iotests/172.out       | 562 +------------------------------
> > >> >>  5 files changed, 30 insertions(+), 669 deletions(-)
> 
> [...]
> 
> > >> 
> > >> Correct.
> > >> 
> > >> This was deprecated in commit 4a27a638e7 "fdc: Deprecate configuring
> > >> floppies with -global isa-fdc" (v5.1.0).  Since then, its use triggers a
> > >> warning:
> > >> 
> > >>     $ qemu-system-x86_64 -nodefaults -M q35 -display none -drive if=none,id=drive-fdc0-0-0 -device isa-fdc,driveA=drive-fdc0-0-0,bootindexA=1
> > >>     qemu-system-x86_64: -device isa-fdc,driveA=drive-fdc0-0-0,bootindexA=1: warning: warning: property isa-fdc.driveA is deprecated
> > >>     Use -device floppy,unit=0,drive=... instead.
> > >> 
> > >> Note the -M q35.  Needed because the default machine type has an onboard
> > >> isa-fdc, which cannot be configured this way.
> > >> 
> > >> Sadly, the commit's update of docs/system/deprecated.rst neglects to
> > >> cover this use.  Looks the series overtaxed my capacity to juggle
> > >> details; my apologies.
> > >> 
> > >> Is libvirt still using these properties?
> > >
> > > Unfortunately yes, but it seems like it ought to be fairly easy to
> > > change the syntax. Just need to figure out what the right way to
> > > detect the availability of the new syntax is. Presumably just look
> > > for existance of the 'floppy' device type ?
> > 
> > Yes.  The device type was added in merge commit fd209e4a7, v2.8.0.
> > 
> > > Can you confirm that switching from -global to the new -device floppy
> > > does /not/ have any live migration impact ?
> > 
> > Yes, it must not affect migration.
> > 
> > When Kevin split the floppy device type off the floppy controller, he
> > had to add some moderately ugly hackery to keep the old qdev properties
> > working.  Think propagate property values to floppy from controller,
> > which otherwise ignores them.
> > 
> > The way you get the values into the floppy device cannot affect the
> > migration data.  Only different values can.
> > 
> > This patch removes a deprecated way.
> 
> Note that when QEMU_CAPS_BLOCKDEV is asserted we format floppies as:
> 
> -blockdev '{"driver":"file","filename":"/tmp/firmware.img",\
> "node-name":"libvirt-2-storage","auto-read-only":true,"discard":"unmap"}' \
> -blockdev '{"node-name":"libvirt-2-format","read-only":false,"driver":"raw",\
> "file":"libvirt-2-storage"}' \
> -device floppy,unit=0,drive=libvirt-2-format,id=fdc0-0-0 \
> -blockdev '{"driver":"file","filename":"/tmp/data.img",\
> "node-name":"libvirt-1-storage","auto-read-only":true,"discard":"unmap"}' \
> -blockdev '{"node-name":"libvirt-1-format","read-only":false,"driver":"qcow2",\
> "file":"libvirt-1-storage"}' \
> -device floppy,unit=1,drive=libvirt-1-format,id=fdc0-0-1 \
> 
> as visible in the test file:
> 
> tests/qemuxml2argvdata/disk-floppy-q35-2_11.x86_64-latest.args
> 
> So libvirt should be in the clear. isa-fdc with driveA/driveB is
> formatted only when the blockdev capability isn't present.

Ahh, excellant, I missed that detailed and worried that we still had
work todo.


Regards,
Daniel
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