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Re: Visopsys 0.83 - Initialization failed while booting as a Virtual Floppy from coreboot/SeaBIOS

Posted: Fri Jan 04, 2019 3:05 pm
by andymc
I'm not much familiar with this world of firmware flashing boot images and whatnot.

Is there any way you could post some instructions about how to set this up in an emulator, such as Qemu or VMware or VirtualBox?

How would the bootloader find out this memory address, of the virtual floppy image it's really booting from? That might be the 'hook' right there. Right now I assume the bootloader thinks it's booting from a real floppy disk - really an emulated one. The loader has to be able to figure out that address, to pass it to the kernel.

Re: Visopsys 0.83 - Initialization failed while booting as a Virtual Floppy from coreboot/SeaBIOS

Posted: Fri Jan 04, 2019 3:20 pm
by andymc
I guess what that Fiwix guy did is to create the ramdisk in the bootloader. So the loader would have to pick a memory address, load the entire emulated floppy into it using the usual int13 calls, then pass that address. But we wouldn't want it to do that under normal circumstances, so there has to be some trigger for it. Perhaps with a custom boot sector.

Is there any part of this that you'd like to try doing? I have limited time (late-night coding sessions) and I'm trying to complete features for the 0.9 release. I'd be happy to work with you on it, though!

Re: Visopsys 0.83 - Initialization failed while booting as a Virtual Floppy from coreboot/SeaBIOS

Posted: Fri Jan 04, 2019 8:12 pm
by qmastery
andymc wrote:
Fri Jan 04, 2019 3:05 pm
Is there any way you could post some instructions about how to set this up in an emulator, such as Qemu or VMware or VirtualBox?
Updated instructions here - viewtopic.php?f=3&t=338

Re: Visopsys 0.83 - Initialization failed while booting as a Virtual Floppy from coreboot/SeaBIOS

Posted: Sat Jan 05, 2019 2:45 am
by andymc
Good instructions, thanks for queueing everything up for me :-)

I'm deep into debugging something else at the moment, but I will give this a go soon.

In the past I've been asked on here about some multiboot stuff, and PXE, and I wonder whether these changes would help to enable all of that - booting from a virtual floppy image.

Rather than a custom boot sector I'd probably go with the creation of an empty file in the image, such /ramdisk, that the bootloader could search for, to trigger this behaviour (as it does with /nograph, which forces text mode operation).