OS booting in Qemu but not in VirtualBox v6

[LIC]

Hi!
I recently updated VirtualBox to version 6.0.4 and it does not want to boot my OS anymore (it did on version 5.x.x). Also the OS is booting fine in Qemu.
I have tried (almost) every system configuration (I/O APIC enabled/disabled, EFI on/off, Hardware clock in UTC time on/off, Chipset PIIX3 / ICH9).

When booting from a SATA or IDE controller my OS as Optical Drive it says "Could not read from the boot medium!" and when I boot with my OS as a floppy disk it goes into my bootloader and my bootloader tells me it cannot read from disk (my bootloader loads the kernel without a problem in Qemu or even in a real machine).

Any idea why VirtualBox does not want to boot my OS?

Thanks fro your help, regards

[Octocontrabass]

When booting from a SATA or IDE controller my OS as Optical Drive it says "Could not read from the boot medium!"

Are you creating a valid El Torito bootable CD image?

and when I boot with my OS as a floppy disk it goes into my bootloader and my bootloader tells me it cannot read from disk (my bootloader loads the kernel without a problem in Qemu or even in a real machine).

That means your code is wrong. Most likely, you didn't initialize all of the registers you're using. I can't tell you any more without seeing your code though.

[LIC]

Is the El Torito mandatory? Because I don't remember having to create such a CD with virtualBox version 5 or with my real machine (USB or SATA boot).

Ok, for my bootloader I'll try to fix it on my own and I'll come back on the forum if I can't figure out the issue.

[Octocontrabass]

Is the El Torito mandatory?

It's mandatory for booting from a CD. You don't need it to boot from hard drives or USB flash drives.

Ok, for my bootloader I'll try to fix it on my own and I'll come back on the forum if I can't figure out the issue.

Good luck!

[LIC]

Okay, thanks!