OSDev.org

I have implemented a floppy driver in my kernel and my boot device is not a valid floppy. The boot device number is 0xFFFFFF (as reported by grub multiboot)

EDIT: I don't think it is a bug in qemu because Virtual box reports the same boot device.

kfreezen wrote:g, kernel problem, or grub bug?  
I have implemented a floppy driver in my kernel and my boot device is not a valid floppy. The boot device number is 0xFFFFFF (as reported by grub multiboot)

EDIT: I don't think it is a bug in qemu because Virtual box reports the same boot device.

I'm fairly sure that the 'standard-ish' boot device number is 0 not 0xFFFFFF for floppy disk drive #0. Maybe check to see if there is something wrong with the way you access the multiboot information?

Oh and it is definitely not a problem with QEMU, BOCHS, GRUB, etc. Many people on here have made workable floppy drivers with the same QEMU and GRUB setup.

I do not believe that I am accessing the boot information wrong because mem_upper is the correct amount of upper memory in my qemu setup.
also, the boot device entry is at mboot_info+12, and the bit indicating that the boot device is valid is 1.

considering that grub/emulators are rarely at fault, it's hard to trust your claim. Hence, please proof that your kernel is correct. Most likely you'll find the bug in the process.

It seems you are misinterpreting the boot_device field. The drive number is only one byte, so it cannot by any chance be 0xFFFFFF. For a floppy the drive number should be 0x00, and the following 3 bytes should be 0xFF, indicating that there are no partitions. Probably your 0xFFFFFF comes just from these 3 bytes.