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.
Sam Eiderman (8): block: Refactor macros - fix tabbing block: Support providing LCHS from user bootdevice: Add interface to gather LCHS scsi: Propagate unrealize() callback to scsi-hd bootdevice: Gather LCHS from all relevant devices bootdevice: Refactor get_boot_devices_list bootdevice: FW_CFG interface for LCHS values hd-geo-test: Add tests for lchs override
bootdevice.c | 158 ++++++++++--- hw/block/virtio-blk.c | 6 + hw/ide/qdev.c | 7 +- hw/nvram/fw_cfg.c | 14 +- hw/scsi/scsi-bus.c | 15 ++ hw/scsi/scsi-disk.c | 14 ++ include/hw/block/block.h | 22 +- include/hw/scsi/scsi.h | 1 + include/sysemu/sysemu.h | 4 + tests/Makefile.include | 2 +- tests/hd-geo-test.c | 565 +++++++++++++++++++++++++++++++++++++++++++++++ 11 files changed, 767 insertions(+), 41 deletions(-)