[LinuxBIOS] Patch for vmlinux amd64 with mkelfImage

Segher Boessenkool segher at kernel.crashing.org
Sun Nov 5 19:38:49 CET 2006

> Are we not going to switch to 64bit mode in LinuxBIOS anyways?

We probably should, PCIe requires 64-bit loads and stores
(well most devices don't need those, but hey).  It also
makes accessing stuff above 4GB way easier, and you can use
all 16 regs without needing prefixes.

>> Or we need to make elfboot in LinuxBIOS to be 64elf aware, and it  
>> need
>> to switch 64bit before load 64bit elf.
> This is the preferred thing I guess, because it will allow us to use
> other 64bit payloads as well without requiring that they do the same
> weird 32->64bit trampolining as Linux does...

That trampoline is really simple actually (well, after I sat
down with it and a lot of paper for a few hours).  A similar
thing is needed to start a 32-bit payload from a 64-bit
firmware of course.

[OT: want to see *really* simple?  On PowerPC it's one bit
only to select between 32- and 64-bit mode.  I'm sooo spoilt].


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