Re: [Qemu-devel] [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 <address@hidden> wrote:
> 
> Thanks Gerd,
> 
> Gentle ping on this.
> 
> Sam
> 
>> On 1 Jul 2019, at 10:41, Gerd Hoffmann <address@hidden> 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 <address@hidden>
>> 
>> cheers,
>> Gerd
>> 
>