Re: Fix for NetBSD Dom0 boot problem

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Wed, Dec 05, 2007 at 06:23:46PM +0100, Christoph Egger wrote:
> 
> Hi Manuel,
> 
> Please update pkgsrc's xenkernel3/patches/patch-ba:
> 
> hg clone http://xenbits.xensource.com/staging/xen-unstable.hg/
> hg diff -p -r16534 -r16535 >netbsd_dom0_bootfix.diff
> 
> The content of netbsd_dom0_bootfix.diff should match this:
> http://xenbits.xensource.com/staging/xen-unstable.hg/rev/c67d024fdd2d
> 
> Add this diff to above patch-ba.
> 
> 
> This fixes a NetBSD Dom0 Xen-amd64 boot problem for me, which I have
> with Xen 3.1.x and Xen-unstable. The Xen crash output is below. The crash
> happened right before NetBSD loaded the symbol table.
> 
> The bug was a trampoline mapping leaking into Dom0s address space.
> And the bug was hit when the Dom0 freed the pagetable.
> 
> Linux Dom0 uses the builder-provided pagetable as its kernel idle pagetable.
> So it never frees the pagetable and so never hit the bad path.
> 
> Oh, I have no idea how you got NetBSD Dom0 booting without that fix.

Yes, I did it see that problem too. It crashes when it tries to unpin the L4
page table provided by Xen. I debugged it and came with patch-cy in
xenkernel3. I now have commited the Xen offical fix, and removed patch-cy
which should have never been there in the first place (the same file patched
twice ...) Thanks !

BTW, I posted this to xen-devel@, but it seems it never went to the list
(I can't see it in the archives), and got no bounce either. Do you know if 
this list is restricted in some way ?

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--