Unable to boot 64bit hello

Julian Stecklina jsteckli at os.inf.tu-dresden.de
Tue Jun 11 15:59:07 CEST 2013


On 06/10/2013 11:28 PM, Daniel Müller wrote:
> Hi,
> 
> On 06/10/13 18:09, Julian Stecklina wrote:
>> This is problem is caused by the way bootstrap works on 64-bit systems.
>> If there is a module at 0x2d0000, bootstrap will overwrite that with its
>> own 64-bit code and then figure out later that things are b0rken.
> Thanks for the explanation. Does this mean this is a general problem for
> 64 bit? And it is on the side of bootstrap? That sounds to me like the

It is a bootstrap implementation problem. Could be fixed. You may
volunteer. ;)

> fix should be on that side as well. Why not change the 0x2d0000 address?
> Anyway, so could I just insert a dummy module and set the
> overlap_allowed flag (or whatever the name is) in the source code?

Adam's grub ( https://os.inf.tu-dresden.de/~adam/grub/ ) can load
modules at higher addresses via the modaddr command, which probably also
solves your problem.

>> I don't know a good workaround for this, except having a bootloader that
>> moves modules out of the way. You might try bender in my firewire
>> toolchain: https://github.com/TUD-OS/morbo
> I might give it a try but I'd rather prefer staying with a more
> mainstream one.

It is not a bootloader per se. It is a multiboot-compliant chainloader
that (among other things) relocates modules to a safe place. So usage in
a e.g. grub would be:

kernel /morbo
module /bootstrap
module /fiasco
...


Julian

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