The second approach failed. There is something missing.
Ah... Hmm... So EFI to BIOS works..
I did run format at Windows 7.
Format? it does not have option to make a floppy bootable.
Yes, this is another option.
I will try as much as possible with what you did EXACTLY so that we can work from a common starting point
This reminds to: Boot from USB/Firewire HD without BIOS support, Fake Signature Method
Wow very interesting thread and work in this field! will be useful in the overall effort.
Ntldr stores a checksum of the MBR at 16 bit mode
Ntldr.exe does detect the boot drive that way.
Post #147 offers a program for cloning signature and checksum.
Does bootmgr do this still?
Does bootmgr uses MBR checksum at a GPT disk too?
Very interesting possibility, but I don't see how it can be... I have stepped through every function call, and there is no checksum of the MBR being calculated anywhere... It seems more like it's trying to call EFI firmware functions to read GPT and one of those set the byte to 01.
Besides, I also edited that memory back to 00.... In which case it takes the other branch, but eventually some other function writes the 01 to the memory... Will check which function when I get time...
Can we use this aproach sowmehow? syslinux memdisk a hard disk image.
But what's the benefit to a floppy image? I don't know.
Yeah, the sooner we get out of floppy land, the better... I mean we're trying to use more modern partitioning with BIOS.. If we can avoid regressing to floppies, that would be good.
joakim did: BOOTMGR with BCD embedded
I was JUST thinking of something like this! Awesome... This will remove the problem of bootmgr not finding bcd.. Eliminates a few issues. Of course, it may not be that hard to give it the facilities to find it the usual way
Does particular value (@0x48e256) flags the floppy mode?
Can you patch bootmgr to enable floppy mode always?
Given bcd embedded and floppy mode always set:
a floppy is not required anymore.
I doubt this is floppy mode either... it simply skips all the useful code when this bit is non-zero. I don't think this is floppy mode.. bcd embedded will be a good stepping stone..
BTW, VMWare player is giving me a strange CPU error on startup when I try using GPT disk with BIOS VM. Dunno what's up... but will test out with VirtualBox
Edited by milindsmart, 01 February 2014 - 07:07 AM.