Re: [Qemu-devel] [PATCH for 2.5? 1/1] DSDT: add floppy-related objects

["Michael S. Tsirkin" <mst@redhat.com>]

On Mon, Dec 14, 2015 at 12:26:17PM +0300, Denis V. Lunev wrote:
> On 12/14/2015 12:21 PM, Michael S. Tsirkin wrote:
> >On Mon, Dec 14, 2015 at 11:22:39AM +0300, Denis V. Lunev wrote:
> >>From: Roman Kagan <rkagan@virtuozzo.com>
> >>
> >>On x86-based systems Linux determines the presence and the type of
> >>floppy drives via a query of a CMOS field.  So does SeaBIOS when
> >>populating the return data for int 0x13 function 0x08.
> >>
> >>Windows doesn't; instead, it requests this information from BIOS via int
> >>0x13/0x08 or through ACPI objects _FDE (Floppy Drive Enumerate) and _FDI
> >>(Floppy Drive Information).  On UEFI systems only ACPI-based detection
> >>is supported.
> >>
> >>QEMU used not to provide those objects in its DSDT; as a result floppy
> >>drives were invisible to Windows on UEFI/OVMF.
> >>
> >>This patch implements those objects in ASL, making the ACPI interpreter
> >>query the CMOS field and populate the objects.  The data values used for
> >>_FDI (which, per ACPI spec, is supposed to be equivalent to BIOS int
> >>0x13/0x08) are taken from SeaBIOS.
> >>
> >>Signed-off-by: Roman Kagan <rkagan@virtuozzo.com>
> >>Signed-off-by: Denis V. Lunev <den@openvz.org>
> >>CC: Michael S. Tsirkin <mst@redhat.com>
> >>CC: Igor Mammedov <imammedo@redhat.com>
> >>CC: Paolo Bonzini <pbonzini@redhat.com>
> >>CC: Richard Henderson <rth@twiddle.net>
> >>CC: Eduardo Habkost <ehabkost@redhat.com>
> >This is not a regression, so I'm inclined not to merge this for 2.5.
> >Pls correct me if I'm wrong.
> >
> 
> this was a question actually.
> 
> Yes, this is not a regression but user observable bug. The floppy
> is not available in Windows UEFI guests and it is not that easy
> to get VirtIO drivers in this case installed especially for root
> disk.
> 
> Den

So it's an important patch but I don't think it's a showstopper for 2.5,
and this is too risky to merge without doing another rc.
This can go into 2.5.1 perhaps.

-- 
MST