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 <kra...@redhat.com> cheers, Gerd
