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

[Samuel Thibault]

Thomas Schwinge, le Thu 01 Oct 2009 17:24:55 +0200, a écrit :
> On Thu, Oct 01, 2009 at 05:23:21PM +0200, Samuel Thibault wrote:
> > Thomas Schwinge, le Thu 01 Oct 2009 17:00:43 +0200, a écrit :
> > > > There's a bootstrap issue: Xen only provides 512KiB of spare bootstrap
> > > > memory, which is not so much to build a pagetable covering 100s of MiB.
> > > 
> > > But why did it work until now?
> > 
> > Because PAE makes page tables twice bigger.
> 
> Again: this system was already using PAE.

Ah, and with PAE you managed to boot with more memory?  How big is your
kernel?  Actually, kernels without debugging symbols & such don't have
the issue because while 512KiB is a minimum, the granularity is 4MiB, of
which the kernel may or may not consume a lot. without debugging
symbols, the kernel typically only consumes 1 or 2 MiB, which leaves
plenty of room for the pagetable.

Samuel