Protected mode from MS-DOS

[Chandra]

Not quite, LGDT takes a reference to a GDTR structure as a regular memory operand. Instead, the problem is the GDTR.offset which should be the field holding the linear address where a virtual one is provided (i.e. your GDT is not some random offset into the IVT)

Oh yes, you're right. LGDT takes a near pointer. Again, there was a big issue with the GDTR structure, BASE of the GDT structure must point to the linear address of the GDT itself so, my post wasn't that stupid afterall.

[rdos]

My recommendation is to write a multiboot compliant kernel and to boot it with GRUB. You can simply install GRUB on your hard drive and use it to boot whatever you like. You don't even need an extra partition for your kernel.

Even better, burn GRUB onto a CD, and put it into your CD-ROM drive when you want multi-boot. That is what I did on my Sony-Vario portable. Then you don''t need to worry about not having a floppy-disc drive, and not about the possibility that the hard-disc modification when installing GRUB would fail.