Re: [Xen-devel] [PATCH] Rlibxl: refuse to try and migrate an HVM guest using qemu-xen

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2012-07-25 at 17:45 +0100, Ian Campbell wrote:
> On Tue, 2012-07-24 at 11:30 +0100, Ian Jackson wrote:
> > Ian Campbell writes ("Re: [Xen-devel] [PATCH] Rlibxl: refuse to try and 
> > migrate an HVM guest using qemu-xen"):
> > > Actually I think -1 == INVALID would be wrong, the -1 here really means
> > > something went wrong internally to libxl. Anyway, I remember now that
> > > the reason I did it this was was to avoid the need to rewrite the other
> > > callsites for 4.2. In 4.3 we should make
> > > libxl__device_model_version_running return ERROR_foo or something valid,
> > > and perhaps add 0 == UNKNOWN as a member of the enum.
> > 
> > Yes.
> > 
> > > For now I think this will do:
> > ..
> > > libxl: refuse to try and migrate an HVM guest using qemu-xen
> > > 
> > > libxl/qemu-upstream currently do not collude together to enable log-dirty 
> > > mode
> > > and therefore migrations are unsafe. Refuse to even try for now.
> > 
> > Acked-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
> 
> Applied, thanks.

Right after I pushed I noticed that gcc 4.6.2 (which is not the one I
typically use for commit testing) fails with:
libxl.c: In function âlibxl_domain_suspendâ:
libxl.c:778:9: error: case value â4294967295â not in enumerated type 
âlibxl_device_model_versionâ [-Werror=switch]

Whereas 4.4.5 (which is my typical commit test and day to day gcc) does
not.

I have pushed the following additional patch to fix this up, tested with
4.4.5 and 4.6.2.

8<---------------

From 365636cac708d4af0907503c07bec530b2dd3a03 Mon Sep 17 00:00:00 2001
From: Ian Campbell <ian.campbell@xxxxxxxxxx>
Date: Wed, 25 Jul 2012 17:52:12 +0100
Subject: [PATCH] libxl: libxl__device_model_version_running should return an int
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

On error it returns -1 and therefore it needs to return int and not
libxl_device_model_enum. Otherwise gcc 4.6.2 complains:

    libxl.c: In function âlibxl_domain_suspendâ:
    libxl.c:778:9: error: case value â4294967295â not in enumerated type 
âlibxl_device_model_versionâ [-Werror=switch]

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
 tools/libxl/libxl_internal.c |    3 +--
 tools/libxl/libxl_internal.h |    3 +--
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/tools/libxl/libxl_internal.c b/tools/libxl/libxl_internal.c
index fbff7d0..24099f5 100644
--- a/tools/libxl/libxl_internal.c
+++ b/tools/libxl/libxl_internal.c
@@ -330,8 +330,7 @@ out:
     return rc;
 }
 
-libxl_device_model_version libxl__device_model_version_running(libxl__gc *gc,
-                                                               uint32_t domid)
+int libxl__device_model_version_running(libxl__gc *gc, uint32_t domid)
 {
     char *path = NULL;
     char *dm_version = NULL;
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 9ffb9d4..1b9b417 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -1515,8 +1515,7 @@ _hidden libxl__json_object *libxl__json_parse(libxl__gc 
*gc, const char *s);
 
   /* Based on /local/domain/$domid/dm-version xenstore key
    * default is qemu xen traditional */
-_hidden libxl_device_model_version
-libxl__device_model_version_running(libxl__gc *gc, uint32_t domid);
+_hidden int libxl__device_model_version_running(libxl__gc *gc, uint32_t domid);
 
 
 /*
-- 
1.7.2.5




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