On 14.11.2013 19:48, M A Young wrote:
> On Thu, 14 Nov 2013, Vladimir 'φ-coder/phcoder' Serbinenko wrote:
> 
>> On 14.11.2013 18:03, M A Young wrote:
>>>
>>>
>>> On Thu, 14 Nov 2013, M A Young wrote:
>>>
>>>> On Wed, 13 Nov 2013, Vladimir 'φ-coder/phcoder' Serbinenko wrote:
>>>>
>>>>> On 13.11.2013 20:06, M A Young wrote:
>>>>>> It doesn't seem to understand sub-partitions. I can get it to work if
>>>>>> the boot files are in /dev/xvda but not in /dev/xvda1 .
>>>>>>
>>>>> insmod part_msdos
>>>>> insmod part_gpt
>>>>
>>>> Right, if I add those to the embedded grub.cfg file I get to the
>>>> standard grub menu and the boot starts. However the boot doesn't get
>>>> very far - it loads the kernel and the initrd file and starts the
>>>> kernel but the kernel doesn't see the virtual disks so it doesn't get
>>>> very far.
>>>
>>> Using xenstore-ls from the dom0 on the guest when the boot stops the
>>> local/domain/2/device/vbd/51712 section looks like
>>>       backend = "/local/domain/0/backend/vbd/2/51712"
>>>       backend-id = "0"
>>>       state = "6\000"
>>>       virtual-device = "51712"
>>>       device-type = "disk"
>>>       ring-ref = "\000"
>>>       event-channel = "\000"
>>>       protocol = "x86_64-abi\000"
>>>
>>> As nothing else has null character endings I suspend that is wrong.
>>>
>> Good catch. Could you test following:
>> diff --git a/grub-core/kern/xen/init.c b/grub-core/kern/xen/init.c
>> index 3bfd99f..ab74543 100644
>> --- a/grub-core/kern/xen/init.c
>> +++ b/grub-core/kern/xen/init.c
>> @@ -256,11 +256,10 @@ grub_xenstore_write_file (const char *dir, const
>> void *buf, grub_size_t len)
>>
>>   grub_memset (&msg, 0, sizeof (msg));
>>   msg.type = XS_WRITE;
>> -  msg.len = dirlen + len + 1;
>> +  msg.len = dirlen + len;
>>   grub_xen_store_send (&msg, sizeof (msg));
>>   grub_xen_store_send (dir, dirlen);
>>   grub_xen_store_send (buf, len);
>> -  grub_xen_store_send ("", 1);
>>   grub_xen_store_recv (&msg, sizeof (msg));
>>   resp = grub_malloc (msg.len + 1);
>>   if (!resp)
> 
> The section is tidied up, ie.
>       backend = "/local/domain/0/backend/vbd/4/51712"
>       backend-id = "0"
>       state = "6"
>       virtual-device = "51712"
>       device-type = "disk"
>       ring-ref = ""
>       event-channel = ""
>       protocol = "x86_64-abi"
> 
> but unfortunately it doesn't help as the boot process sticks at the same
> point. I notice this section is in state 6 which apparently is "closed".
> I wonder if the kernel expecting something else.
Possible. I'd try this (on top of previous patch):
diff --git a/grub-core/disk/xen/xendisk.c b/grub-core/disk/xen/xendisk.c
index c449848..829da3d 100644
--- a/grub-core/disk/xen/xendisk.c
+++ b/grub-core/disk/xen/xendisk.c
@@ -449,5 +449,8 @@ grub_xendisk_fini (void)
       grub_xen_free_shared_page (virtdisks[i].shared_page);
 
       grub_xen_event_channel_op (EVTCHNOP_close, &close_op);
+
+      /* Prepare for handoff.  */
+      grub_xenstore_write_file (fdir, "0", 1);
     }
 }

> 
>     Michael Young