AMD64 Support

Ernesto Bascon ebasconp at
Tue Feb 13 15:27:59 PST 2007

We can cooperate.

I am a C, C++, some x86 assembler, Java, C# application developer, so,
I have no experience working on kernel development!
If you could "show me the way" from the start, should be perfect for me  :)
> Simon "corecode" Schubert and Thomas E. Spanjaard gave me a lot of
> support about this topic several days ago, but I am really newbie and
> have no the needed skills (yet) to work on something so "core" and
> technical :( But I wanna help! :)
If you can provide me the details that you got from other developers
that would be gr8. I can digest the technicality.
Simon Schubert contacted me with Thomas E. Spanjaard, he has been
working on the port to AMD64; Thomas wrote me this:
"Well, basically I've only focussed on locore and pmap right now. I have
some header files done, locore.s, and I'm still shuffling files around
between platform/pc64 and cpu/x86_64. I think that once the layout of
KVA and the pmap code are reasonably done, the rest of the kernel side
can be worked on.
As far as the VA space is concerned, I am thinking that we shouldn't
reserve the entire upper half of usable VA space (the 256 uppermost
entries in the PML4 that's active), because I don't want to consume too
much memory for the kernel, even though the usable VA space is (way)
larger than the usable PA space. I don't think the kernel will ever need
the full 128TiB the upper half of usable VA space maps; Whereas it is
currently hard to imagine DFly ever running on machines with such
amounts of RAM, I don't see it impossible in the future; and I'd rather
have userland apps be able to consume >128TiB of memory, than the kernel
having 128TiB which it won't ever use. Ofcourse, given the limitations
in the current x86_64 implementations regarding PA space, that's not
really realistic right now, but I guess you got my point."



More information about the Kernel mailing list