Re: [Xen-devel] regression with c/s 21223

[Jim Fehlig <jfehlig@xxxxxxxxxx>]

Keir Fraser wrote:
> On 07/05/2010 04:36, "Jim Fehlig" <jfehlig@xxxxxxxxxx> wrote:
>
>   
>> Frankly, I'm not sure how best to handle this case.  The current
>> philosophy seems to be treat all 'tap:foo' devices as blktap2 (see c/s
>> 19874 - author cc'd), but fall back to blktap1 if blktap2 is not found
>> when domU is started.  I'm certainly having problems differentiating
>> between the two in to_sxp().
>>
>> Any suggestions on how to prevent the bug reported in [1] without this
>> new regression?
>>     
>
> Way outside my comfort zone with xend I'm afraid. Do you think we need
> explicit differentiation between tap and tap2?
>   

That is certainly an approach we are considering for our Xen 4.0-based
packages - see attached patch.  As mentioned previously, we are not yet
supporting blktap2 so such a change seems appropriate in our case.

I'm hoping some of the folks that integrated blktap2 in xend can provide
suggestions.

Regards,
Jim

Index: xen-4.0.0-testing/tools/python/xen/xm/main.py
===================================================================
--- xen-4.0.0-testing.orig/tools/python/xen/xm/main.py
+++ xen-4.0.0-testing/tools/python/xen/xm/main.py
@@ -2629,8 +2629,10 @@ def xm_usb_list_assignable_devices(args)
 def parse_block_configuration(args):
     dom = args[0]
 
-    if args[1].startswith('tap:'):
+    if args[1].startswith('tap2:'):
         cls = 'tap2'
+    elif args[1].startswith('tap:'):
+        cls = 'tap'
     else:
         cls = 'vbd'
 
Index: xen-4.0.0-testing/tools/python/xen/xm/create.py
===================================================================
--- xen-4.0.0-testing.orig/tools/python/xen/xm/create.py
+++ xen-4.0.0-testing/tools/python/xen/xm/create.py
@@ -791,8 +791,10 @@ def configure_disks(config_devs, vals):
     """Create the config for disks (virtual block devices).
     """
     for (uname, dev, mode, backend, protocol) in vals.disk:
-        if uname.startswith('tap:'):
+        if uname.startswith('tap2:'):
             cls = 'tap2'
+        elif uname.startswith('tap:'):
+            cls = 'tap'
         else:
             cls = 'vbd'
 

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