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Re: [Qemu-devel] [PULL 48/49] i386: populate floppy drive information in
From: |
Roman Kagan |
Subject: |
Re: [Qemu-devel] [PULL 48/49] i386: populate floppy drive information in DSDT |
Date: |
Wed, 10 Feb 2016 20:24:21 +0300 |
User-agent: |
Mutt/1.5.24 (2015-08-30) |
On Wed, Feb 10, 2016 at 11:14:30AM -0500, John Snow wrote:
> On 02/09/2016 01:48 PM, Michael S. Tsirkin wrote:
> > On Tue, Feb 09, 2016 at 07:36:12PM +0100, Laszlo Ersek wrote:
> >> Implementing this in QEMU would require:
> >> - inventing virt-only registers for the FDC that provide the current
> >> disk geometry,
>
> We do secretly have these registers, but of course there's no spec to
> interpreting what they mean. For instance, what do they read when the
> drive is empty? I am not sure that information is codified in the ACPI spec.
There are various possibilities, like returning False for the
corresponding drive in _FDE (Floppy Disk Enumerate) object, or returning
0 aka unknown as drive type in _FDI. Anyway I'd hate needing to expose
all of that in an ACPI-accessible form, this is going to become too fat.
> Could be wrong, you seemed to indicate that the ACPI spec said that the
> info matches what you get from a certain legacy bios routine, but I
> don't know the specifics of that routine, either.
Indeed, it's supposed to do the same as
https://en.wikipedia.org/wiki/INT_13H#INT_13h_AH.3D08h:_Read_Drive_Parameters
and, as I wrote in another mail, the SeaBIOS implementation here is
rather simplistic.
> Roman, does the 0xFF "empty disk geometry" hack appear to work for
> Windows 10?
>
> Maybe it's fine enough as-is, as per Laszlo's good synopsis here.
I'll test and let you know.
Roman.
- [Qemu-devel] [PULL 48/49] i386: populate floppy drive information in DSDT, (continued)
- [Qemu-devel] [PULL 48/49] i386: populate floppy drive information in DSDT, Michael S. Tsirkin, 2016/02/04
- Re: [Qemu-devel] [PULL 48/49] i386: populate floppy drive information in DSDT, Igor Mammedov, 2016/02/05
- Re: [Qemu-devel] [PULL 48/49] i386: populate floppy drive information in DSDT, Roman Kagan, 2016/02/08
- Re: [Qemu-devel] [PULL 48/49] i386: populate floppy drive information in DSDT, John Snow, 2016/02/08
- Re: [Qemu-devel] [PULL 48/49] i386: populate floppy drive information in DSDT, Roman Kagan, 2016/02/09
- Re: [Qemu-devel] [PULL 48/49] i386: populate floppy drive information in DSDT, John Snow, 2016/02/09
- Re: [Qemu-devel] [PULL 48/49] i386: populate floppy drive information in DSDT, Laszlo Ersek, 2016/02/09
- Re: [Qemu-devel] [PULL 48/49] i386: populate floppy drive information in DSDT, Michael S. Tsirkin, 2016/02/09
- Re: [Qemu-devel] [PULL 48/49] i386: populate floppy drive information in DSDT, John Snow, 2016/02/10
- Re: [Qemu-devel] [PULL 48/49] i386: populate floppy drive information in DSDT, Michael S. Tsirkin, 2016/02/10
- Re: [Qemu-devel] [PULL 48/49] i386: populate floppy drive information in DSDT,
Roman Kagan <=
- Re: [Qemu-devel] [PULL 48/49] i386: populate floppy drive information in DSDT, Roman Kagan, 2016/02/10
- Re: [Qemu-devel] [PULL 48/49] i386: populate floppy drive information in DSDT, John Snow, 2016/02/10
- Re: [Qemu-devel] [PULL 48/49] i386: populate floppy drive information in DSDT, Roman Kagan, 2016/02/10
- Re: [Qemu-devel] [PULL 48/49] i386: populate floppy drive information in DSDT, John Snow, 2016/02/10
- Re: [Qemu-devel] [PULL 48/49] i386: populate floppy drive information in DSDT, Kevin O'Connor, 2016/02/13
- Re: [Qemu-devel] [PULL 48/49] i386: populate floppy drive information in DSDT, Laszlo Ersek, 2016/02/14
- Re: [Qemu-devel] [PULL 48/49] i386: populate floppy drive information in DSDT, Michael S. Tsirkin, 2016/02/14
- Re: [Qemu-devel] [PULL 48/49] i386: populate floppy drive information in DSDT, Roman Kagan, 2016/02/17
- Re: [Qemu-devel] [PULL 48/49] i386: populate floppy drive information in DSDT, Roman Kagan, 2016/02/10
[Qemu-devel] [PULL 47/49] expose floppy drive geometry and CMOS type, Michael S. Tsirkin, 2016/02/04