[SeaBIOS] Re: [QEMU] [PATCH v5 0/8] Add Qemu to SeaBIOS LCHS interface

[Sam Eiderman]

Gentle ping.

Sam
> On 8 Jul 2019, at 20:30, Sam Eiderman  wrote:
>
> Thanks Gerd,
>
> Gentle ping on this.
>
> Sam
> > On 1 Jul 2019, at 10:41, Gerd Hoffmann  wrote:
> >
> > On Wed, Jun 26, 2019 at 03:39:40PM +0300, Sam Eiderman wrote:
> > > v1:
> > >
> > > Non-standard logical geometries break under QEMU.
> > >
> > > A virtual disk which contains an operating system which depends on
> > > logical geometries (consistent values being reported from BIOS INT13
> > > AH=08) will most likely break under QEMU/SeaBIOS if it has non-standard
> > > logical geometries - for example 56 SPT (sectors per track).
> > > No matter what QEMU will guess - SeaBIOS, for large enough disks - will
> > > use LBA translation, which will report 63 SPT instead.
> > >
> > > In addition we can not enforce SeaBIOS to rely on phyiscal geometries at
> > > all. A virtio-blk-pci virtual disk with 255 phyiscal heads can not
> > > report more than 16 physical heads when moved to an IDE controller, the
> > > ATA spec allows a maximum of 16 heads - this is an artifact of
> > > virtualization.
> > >
> > > By supplying the logical geometies directly we are able to support such
> > > "exotic" disks.
> > >
> > > We will use fw_cfg to do just that.
> > >
> > > v2:
> > >
> > > Fix missing parenthesis check in
> > >   "hd-geo-test: Add tests for lchs override"
> > >
> > > v3:
> > > Rename fw_cfg key to "bios-geometry".
> > > Remove "extendible" interface.
> > > Add cpu_to_le32 fix as Laszlo suggested or big endian hosts
> > > Fix last qtest commit - automatic docker tester for some reason does not have qemu-img set
> > >
> > > v4:
> > > Change fw_cfg interface from mixed textual/binary to textual only
> > >
> > > v5:
> > > Fix line > 80 chars in tests/hd-geo-test.c
> >
> > Reviewed-by: Gerd Hoffmann
> >
> > cheers,
> > Gerd