Re: [PATCH] qemu-xen-3.4-testing: Fix read-only image file handling

[Michal Novotny <minovotn@redhat.com>]

On 06/07/2010 01:45 PM, Pasi Kärkkäinen wrote:
> On Mon, Jun 07, 2010 at 01:21:21PM +0200, Michal Novotny wrote:
>    
>> Well, I'm still having some tools issues, mainly:
>>
>> Error: (111, 'Connection refused')
>>
>> Any guess what may be going wrong? Booted grub entry:
>>
>> title Red Hat Enterprise Linux Server (2.6.31.13-xen HV, nolog)
>>          root (hd1,6)
>>          kernel /xen-4.1-unstable.gz
>>          module /vmlinuz-2.6.31.13 ro root=LABEL=/rhel2 rhgb quiet selinux=0
>>          module /initrd-2.6.31.13.img
>>
>> Mount is having `xenfs on /proc/xen type xenfs (rw)`. Any guess what may
>> be going wrong?
>>
>>      
>
> Do you have xen-evtchn driver loaded?
>
>
> -- Pasi
>
>    

Well, no, and doesn't seem to be installed/probed:

# modprobe xen-evtchn
# lsmod | grep xen-evtchn
#

So there's the problem :(

Michal

>    
>> Thanks,
>> Michal
>>
>> On 06/04/2010 12:42 PM, Pasi Kärkkäinen wrote:
>>      
>>> On Fri, Jun 04, 2010 at 11:37:51AM +0200, Michal Novotny wrote:
>>>
>>>        
>>>> Oh, one more thing I've discovered now. Since the codebase for
>>>> qemu-xen-unstable is looking the same like for qemu-xen-3.4-testing and
>>>> the patch is applicable without any modifications it could be working
>>>> for xen-4.1 unstable as well, unfortunately I was not able to boot PVOPS
>>>> kernel since it always ends up in kernel panic, maybe the missing
>>>> drivers or something like that.
>>>>
>>>>
>>>>          
>>> What kernel version? Did you use xen/stable-2.6.32.x branch from xen.git?
>>>
>>> See my example .config files from:
>>> http://wiki.xensource.com/xenwiki/XenParavirtOps in the "troubleshooting" section.
>>>
>>> Works on F12/F13 dom0's.
>>>
>>> For el5 dom0 you might need these:
>>> http://wiki.xensource.com/xenwiki/2.6.18-to-2.6.31-and-higher
>>>
>>> aka
>>> CONFIG_SYSFS_DEPRECATED=y
>>> CONFIG_SYSFS_DEPRECATED_V2=y
>>>
>>> Also atm I think you need CONFIG_XEN_XENBUS_FRONTEND=y in the .config
>>> because of the recently added pv-on-hvm drivers (you'll get build failure without that option),
>>> so you need XEN_PCIDEV_FRONTEND XEN_BLKDEV_FRONTEND or XEN_NETDEV_FRONTEND or XEN_FBDEV_FRONTEND needs to be =y.
>>>
>>> -- Pasi
>>>
>>>
>>>
>>>        
>>>> On 06/03/2010 04:12 PM, Michal Novotny wrote:
>>>>
>>>>          
>>>>> Oh, just one more thing that should be mentioned:
>>>>>
>>>>> When you want to mount an image that is set as read-only in the domain
>>>>> configuration file but you omit to set mode to read-only it results
>>>>> into I/O errors when processing the requests. Remounting as read-only
>>>>> or unmounting and remounting using the `mount /dev/* /path/to/mount -o
>>>>> ro` shall do the mounting the correct way, i.e. with no I/O errors, so
>>>>> make sure you mount those disks as read-only otherwise you can be
>>>>> getting errors like:
>>>>>
>>>>> end_request: I/O error, dev hdb, sector 52
>>>>>
>>>>> Buffer I/O error on device hdb1, logical block 1
>>>>>
>>>>> lost page write due to I/O error on hdb1
>>>>>
>>>>>
>>>>> and for IDE devices you'll be getting several additional DeviceFault
>>>>> errors since mounting the device read-write (default setting) writes
>>>>> some data onto a disk at the mount-time.
>>>>>
>>>>> Michal
>>>>>
>>>>> On 06/03/2010 04:04 PM, Michal Novotny wrote:
>>>>>
>>>>>            
>>>>>> [Well, I did send an e-mail to the list using git but it's not here
>>>>>> so I'm forwarding the e-mail to the list for sure:]
>>>>>>
>>>>>> Hi,
>>>>>> this is the patch for qemu-xen-3.4-testing to fix the read-only
>>>>>> image file handling since the image file was always treated as
>>>>>> read-write which means that all the HVM guests were able to
>>>>>> write to all the disk images available in domain configuration
>>>>>> file no matter what the mode of the image was defined. This
>>>>>> patch fixes this functionality to honor the O_RDONLY in the
>>>>>> BDRV_O_ACCESS flag in block.c and also fixes the IDE and SCSI
>>>>>> interfaces that uses it.
>>>>>>
>>>>>> It's been tested on RHEL-5 with xen-3.4-testing version of
>>>>>> upstream xen with xen-3.4-testing qemu implementation.
>>>>>>
>>>>>> For SCSI devices the DATA PROTECT request sense has been added
>>>>>> as found at: http://en.wikipedia.org/wiki/SCSI_Request_Sense_Command
>>>>>>
>>>>>> file no matter what the mode of the image was defined. This
>>>>>> patch fixes this functionality to honor the O_RDONLY in the
>>>>>> BDRV_O_ACCESS flag in block.c and also fixes the IDE and SCSI
>>>>>> interfaces that uses it.
>>>>>>
>>>>>> It's been tested on RHEL-5 with xen-3.4-testing version of
>>>>>> Michal
>>>>>>
>>>>>> Signed-off-by: Michal Novotny<minovotn@redhat.com>
>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> Xen-devel mailing list
>>>>>> Xen-devel@lists.xensource.com
>>>>>> http://lists.xensource.com/xen-devel
>>>>>>
>>>>>>              
>>>>>
>>>>>            
>>>> -- 
>>>> Michal Novotny<minovotn@redhat.com>, RHCE
>>>> Virtualization Team (xen userspace), Red Hat
>>>>
>>>>
>>>> _______________________________________________
>>>> Xen-devel mailing list
>>>> Xen-devel@lists.xensource.com
>>>> http://lists.xensource.com/xen-devel
>>>>
>>>>          
>>
>> -- 
>> Michal Novotny<minovotn@redhat.com>, RHCE
>> Virtualization Team (xen userspace), Red Hat
>>
>>      
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>    


-- 
Michal Novotny<minovotn@redhat.com>, RHCE
Virtualization Team (xen userspace), Red Hat