Re: Xen domU vs. more than 652 MiB of RAM

[Samuel Thibault]

Thomas Schwinge, le Thu 01 Oct 2009 18:22:56 +0200, a écrit :
> `gnumach-xen' is the stripped version of `gnumach-xen.', without your
> patch.  Which one I use of these two doesn't make a difference.  But
> then, are the debug section being mapped at all?

IIRC Xen's loader is quite dumb, I don't have the time to investigate.

> But, and I guess that's what you meant: if I build a ``--disable-kdb''
> kernel, which is 386364 stripped, then I can go somewhere above 700,

It possibly has given you the room for the pagetable yes.

Oh wait, now I remember, I said 4MiB granularity. Actually with PAE it's
even 2MiB granularity. A 700MiB pagetable needs 700M/4K*8=1.3MiB bytes.

> but below 800 MiB.  Your patch is meant to cancel this limitation?

We'll always have the 800MiB limitation anyway (due to virtual
projectinos needing room in the 1GiB kernel virtual space). In principle
the limitation is properly handled by GNU Mach (i.e. free memory is
capped), but there may still be bugs.

Samuel