Re: [PATCH] i386: modified CONFIG_PHYSICAL_ALIGN

[Rusty Russell <rusty@rustcorp.com.au>]

On Tue, 2007-08-14 at 05:29 +0200, Andi Kleen wrote:
> On Tue, Aug 14, 2007 at 09:55:50AM +0900, Yoshimi Ichiyanagi wrote:
> 
> How is this related to virtualization?
> 
> > The problem is, if you compile x86_64 kernel, the value of 
> > CONFIG_PHYSICAL_ALIGN will be fixed, and the next time you compile i386 
> > kernel, previous CONFIG_PHYSICAL_ALIGN value of x86_64(default: 2MB) will 
> > be used by default.
> 
> 2/4MB is better for i386 too for PAE/non PAE because
> it will use less TLB entries. I guess it's better to just change
> the defaults.
> 
> Anyways, both values should work, or did you see 
> failures?

I had this problem too: Lguest assumes 1MB when loading bzImages, and
the only time that gets changed is when building from an x86-64 config.
I considered it purely an lguest issue.

The correct fix is to have lguest run bzImages rather than trying to
unpack them itself, but that requires a bootloader change, and the
proposals to do that got lost in a flurry of far more ambitious patches.

Jeremy would know the status of that work...
Rusty.