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From: Aurelien Jarno <aurelien@aurel32.net>
To: kvm@vger.kernel.org
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Subject: Out of sync shadow core breaks Hurd
Date: Wed, 12 Nov 2008 20:00:37 +0100	[thread overview]
Message-ID: <20081112190037.GA4009@volta.aurel32.net> (raw)

Hi,

Starting with kvm-76 (and including kvm-79), Hurd does not boot anymore
under KVM. The ext2fs translator issues a strange error message:

| Hurd server bootstrap: ext2fs.static[device:hd0s3] execext2fs.static: /build/bui
| ldd/hurd-20080607/build-tree/hurd/ext2fs/dir.c:494: dirscanblock: Assertion `dp-
| >dn->dirents[idx] == -1 || dp->dn->dirents[idx] == nentries' failed.           -
| >dn->dirents[idx] == -1 || dp->dn->dirents[idx] == nentries' failed.

Bisecting the problem, I have found that it comes from this patch:

| 641fb03992b20aa640781a245f6b7136f0b845e4 is first bad commit
| commit 641fb03992b20aa640781a245f6b7136f0b845e4
| Author: Marcelo Tosatti <mtosatti@redhat.com>
| Date:   Tue Sep 23 13:18:39 2008 -0300
| 
|     KVM: MMU: out of sync shadow core v2
| 
|     Allow guest pagetables to go out of sync.
| 
|     Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
|     Signed-off-by: Avi Kivity <avi@redhat.com>

The problem can be workarounded loading the kvm module with 
oos_shadow=0.

The easiest way to reproduce the problem is to download a ready to use
Hurd image [1]. The error message from the ext2fs translator is not
exactly the same, but it still fails.

Aurelien

[1] http://ftp.debian-ports.org/debian-cd/hurd-i386/current/debian-hurd-k16-qemu.img.tar.gz

-- 
  .''`.  Aurelien Jarno	            | GPG: 1024D/F1BCDB73
 : :' :  Debian developer           | Electrical Engineer
 `. `'   aurel32@debian.org         | aurelien@aurel32.net
   `-    people.debian.org/~aurel32 | www.aurel32.net

             reply	other threads:[~2008-11-12 19:00 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-11-12 19:00 Aurelien Jarno [this message]
2008-11-15 12:15 ` Out of sync shadow core breaks Hurd Marcelo Tosatti
2008-11-20  9:48 ` Marcelo Tosatti
2008-11-25  9:57   ` Aurelien Jarno
2008-11-25 16:52     ` Aurelien Jarno

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