Re: libvirt, libxl and QDISKs

[David Scott <dave.scott@eu.citrix.com>]

[-- Attachment #1: Type: text/plain, Size: 1798 bytes --]

On 26/04/13 05:50, Jim Fehlig wrote:
> Jim Fehlig wrote:
>> Ian Campbell wrote:
>>
>>> On Thu, 2013-04-25 at 14:22 +0100, Dave Scott wrote:
>>>
>>>
>>>> On 25/04/13 13:43, Ian Campbell wrote:
>>>>
>>>>
>>>
>>>
>>>> It looks like we could define a "qdisk" driverName.
>>>>
>>>>
>>> Yes, I think this would work. WRT to your comment below it looks like
>>> other libvirt drivers call this driver "qemu".
>>>
>>>
>>
>> IMO, we should just extend the above to map driverName 'qemu' to backend
>> 'qdisk'.  But what about the formats?  I though qdisk could handle all
>> of them, particularly with qemu-upstream, even vmdk?
>>
>
> Something like the attached, which seems to work well for me when
> specifying driverName = qemu, e.g.
>
>      <disk type='file' device='disk'>
>        <driver name='qemu'/>
>        <source file='/var/lib/xen/images/sles11sp2-pv/disk0.raw'/>
>        <target dev='xvda' bus='xen'/>
>      </disk>

This also works for me!

On a related note, what do you think about the attached patch? It allows 
the user to select a non-default qemu via the <emulator> element. My 
domain XML looked like this:

   <devices>
     <emulator>/usr/lib/xen/bin/qemu-system-i386</emulator>
     <disk device="disk" type="network">
       <driver name='qemu'/>
       <source protocol="rbd" name="rbd:rbd/ubuntu1204.img"/>
       <target dev="hda"/>
     </disk>
     <graphics type="vnc" port="-1" autoport="yes" listen="0.0.0.0"/>
   </devices>

Now that upstream qemu is the default in xen-4.3, it seems useful to be 
able to select the traditional qemu for older VMs.

Also I backported this to my xen-4.2 system and used this patch + your 
patch + the previous 'stat()' fix to successfully start a VM on ceph 
storage via libvirt + libxl (my quest is almost complete!)

Cheers,
Dave



[-- Attachment #2: libxl-make-emulator.patch --]
[-- Type: text/x-patch, Size: 1378 bytes --]

diff --git a/src/libxl/libxl_conf.c b/src/libxl/libxl_conf.c
index f549a5d..abbd3c0 100644
--- a/src/libxl/libxl_conf.c
+++ b/src/libxl/libxl_conf.c
@@ -811,6 +811,30 @@ libxlMakeCapabilities(libxl_ctx *ctx)
 }
 
 int
+libxlMakeEmulator(virDomainDefPtr def, libxl_domain_config *d_config)
+{
+    /* No explicit override means use the default */
+    if (!def->emulator) {
+        return 0;
+    }
+    if (strstr(def->emulator, "/qemu-system-")) {
+        d_config->b_info.device_model_version =
+            LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN;
+        return 0;
+    }
+    if (strstr(def->emulator, "/qemu-dm")) {
+        d_config->b_info.device_model_version =
+            LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN_TRADITIONAL;
+        return 0;
+    }
+    virReportError(VIR_ERR_INTERNAL_ERROR,
+                   _("libxenlight doesn't support emulator '%s'"),
+                   def->emulator);
+    return -1;
+}
+
+
+int
 libxlBuildDomainConfig(libxlDriverPrivatePtr driver,
                        virDomainDefPtr def, libxl_domain_config *d_config)
 {
@@ -834,6 +858,10 @@ libxlBuildDomainConfig(libxlDriverPrivatePtr driver,
         goto error;
     }
 
+    if (libxlMakeEmulator(def, d_config) < 0) {
+        goto error;
+    }
+
     d_config->on_reboot = def->onReboot;
     d_config->on_poweroff = def->onPoweroff;
     d_config->on_crash = def->onCrash;

[-- Attachment #3: Type: text/plain, Size: 126 bytes --]

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
http://lists.xen.org/xen-devel