On 8 Jul 2019, at 20:30, Sam Eiderman email@example.com wrote:
Gentle ping on this.
On 1 Jul 2019, at 10:41, Gerd Hoffmann firstname.lastname@example.org wrote:
On Wed, Jun 26, 2019 at 03:39:40PM +0300, Sam Eiderman wrote:
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.
Fix missing parenthesis check in "hd-geo-test: Add tests for lchs override"
- 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
- Change fw_cfg interface from mixed textual/binary to textual only
- Fix line > 80 chars in tests/hd-geo-test.c
Reviewed-by: Gerd Hoffmann email@example.com