Xen devel - Nov 2012 - [PATCH] fix vfb related assertion problem when starting pv-domU

When a config-file for a pv-domU has a vfb section with a vnc=0 option then a 
"xl create" for that domU crashes with the message


xl: libxl.c:252: libxl_defbool_val: Assertion
`!libxl_defbool_is_default(db)''
failed.


and the domU hangs early in the start.

This patch fixes the cause of the assertion and let the domU start normally.

This problem exists since xen 4.2.

--- tools/libxl/libxl.c.org	2012-11-01 01:35:52.000000000 +0000
+++ tools/libxl/libxl.c	2012-11-01 01:36:20.000000000 +0000
@@ -2949,6 +2949,8 @@ int libxl__device_vfb_setdefault(libxl__
         }
 
         libxl_defbool_setdefault(&vfb->vnc.findunused, true);
+    } else {
+        libxl_defbool_setdefault(&vfb->vnc.findunused, false);
     }
 
     libxl_defbool_setdefault(&vfb->sdl.enable, false);

On Thu, 2012-11-01 at 02:18 +0000, Ronny Hegewald wrote:
> When a config-file for a pv-domU has a vfb section with a vnc=0 option then
a
> "xl create" for that domU crashes with the message
> 
> 
> xl: libxl.c:252: libxl_defbool_val: Assertion
`!libxl_defbool_is_default(db)''
> failed.
> 
> 
> and the domU hangs early in the start.
> 
> This patch fixes the cause of the assertion and let the domU start
normally.
> 
> This problem exists since xen 4.2.
This seems like a good fix, in order to for us to apply it please can
you "sign off" as described in
http://wiki.xen.org/wiki/Submitting_Xen_Patches#Signing_off_a_patch

I do wonder if perhaps libxl__device_vfb_add ought to be gating a bunch
of those accesses on vnc.enabled though.

Ian.
> 
> --- tools/libxl/libxl.c.org	2012-11-01 01:35:52.000000000 +0000
> +++ tools/libxl/libxl.c	2012-11-01 01:36:20.000000000 +0000
> @@ -2949,6 +2949,8 @@ int libxl__device_vfb_setdefault(libxl__
>          }
>  
>          libxl_defbool_setdefault(&vfb->vnc.findunused, true);
> +    } else {
> +        libxl_defbool_setdefault(&vfb->vnc.findunused, false);
>      }
>  
>      libxl_defbool_setdefault(&vfb->sdl.enable, false);
> 
> 
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel

When a config-file for a pv-domU has a vfb section with a vnc=0 option then a 
"xl create" for that domU crashes with the message


xl: libxl.c:252: libxl_defbool_val: Assertion
`!libxl_defbool_is_default(db)''
failed.


and the domU hangs early in the start.

This patch fixes the cause of the assertion and let the domU start normally.

This problem exists since xen 4.2.

Signed-off-by: Ronny Hegewald@online.de

--- tools/libxl/libxl.c.org	2012-11-01 01:35:52.000000000 +0000
+++ tools/libxl/libxl.c	2012-11-01 01:36:20.000000000 +0000
@@ -2949,6 +2949,8 @@ int libxl__device_vfb_setdefault(libxl__
         }
 
         libxl_defbool_setdefault(&vfb->vnc.findunused, true);
+    } else {
+        libxl_defbool_setdefault(&vfb->vnc.findunused, false);
     }
 
     libxl_defbool_setdefault(&vfb->sdl.enable, false);

>
> Signed-off-by: Ronny Hegewald@online.de
>
Somehow the sign off gone wrong. it was supposed to be

Signed-off-by: Ronny Hegewald <Ronny.Hegewald@online.de>

On Sat, 2012-11-03 at 02:55 +0000, Ronny Hegewald wrote:
> >
> > Signed-off-by: Ronny Hegewald@online.de
> >
> 
> Somehow the sign off gone wrong. it was supposed to be
> 
> Signed-off-by: Ronny Hegewald <Ronny.Hegewald@online.de>
Acked-by: Ian Campbell <ian.campbell@citrix.com> and applied, thanks.

For future reference can you generate patches so they apply with "patch
-p1", the tooling copes much better with those sorts of patches.

e.g.:
--- tools/libxl/libxl.c.org
+++ tools/libxl/libxl.c

should look like:
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
or:
--- xen.orig/tools/libxl/libxl.c
+++ xen/tools/libxl/libxl.c
or:
--- xen/tools/libxl/libxl.c.orig
+++ xen/tools/libxl/libxl.c
etc.

Tools like git format-patch + send-email or hg export / hg email (the
last described in http://wiki.xen.org/wiki/Submitting_Xen_Patches) do
this automatically I think.

Thanks,
Ian.

On Tuesday 13 November 2012, Ian Campbell wrote:
> On Sat, 2012-11-03 at 02:55 +0000, Ronny Hegewald wrote:
> > > Signed-off-by: Ronny Hegewald@online.de
> >
> > Somehow the sign off gone wrong. it was supposed to be
> >
> > Signed-off-by: Ronny Hegewald <Ronny.Hegewald@online.de>
>
> Acked-by: Ian Campbell <ian.campbell@citrix.com> and applied, thanks.
>
Wouldn''t this patch also be appropriate for the 4.2 stable branch?

On Wed, 2012-11-21 at 23:50 +0000, Ronny Hegewald wrote:
> On Tuesday 13 November 2012, Ian Campbell wrote:
> > On Sat, 2012-11-03 at 02:55 +0000, Ronny Hegewald wrote:
> > > > Signed-off-by: Ronny Hegewald@online.de
> > >
> > > Somehow the sign off gone wrong. it was supposed to be
> > >
> > > Signed-off-by: Ronny Hegewald <Ronny.Hegewald@online.de>
> >
> > Acked-by: Ian Campbell <ian.campbell@citrix.com> and applied,
thanks.
> >
> 
> Wouldn''t this patch also be appropriate for the 4.2 stable branch?
Yes, I think so.

Ian, this is 26145:8b93ac0c93f3 in unstable.

Ian.