Re: [Xen-devel] [BUG] libxl: error: libxl_device.c:301:libxl__device_disk_set_backend: no suitable backend for disk

["Alex Braunegg" <alex.braunegg@xxxxxxxxx>]

Hi Ian

Is there anything I can do to help here at all to provide further details? I am 
happy to do any local side diagnosing on this issue.

When performing validation testing of Xen code from a developers point of view 
- what packages / versions are these tests performed against? Perhaps there is 
something local to my system that is contributing to xl not being able to issue 
the cd-eject / cd-insert command properly. Maybe a kernel config option 
relating to Xen?

Kernel / Xen / Qemu package list below:

[root@mynas-s5000xvn ~]# rpm -qa | grep xen
mynas-xen-drivers-1.4.0-201601271353.el6.x86_64
xen-runtime-4.6.0-12.el6.x86_64
xen-doc-4.6.0-11.el6.x86_64
xen-hypervisor-4.6.0-12.el6.x86_64
xen-ocaml-4.6.0-12.el6.x86_64
xen-4.6.0-12.el6.x86_64
xen-licenses-4.6.0-12.el6.x86_64
xen-libs-4.6.0-12.el6.x86_64

[root@mynas-s5000xvn ~]# rpm -qa | grep qemu
qemu-img-0.12.1.2-2.479.el6_7.4.x86_64

[root@mynas-s5000xvn ~]# rpm -qa | grep kernel
kernel-firmware-4.3.4-2.el6.x86_64
kernel-4.3.4-1.el6.x86_64
kernel-4.3.4-2.el6.x86_64
dracut-kernel-004-388.el6.noarch
kernel-3.14.58-3.el6.x86_64

[root@mynas-s5000xvn ~]# uname -a
Linux mynas-s5000xvn.localdomain 4.3.4-2.el6.x86_64 #1 SMP Tue Feb 9 10:38:50 
EST 2016 x86_64 x86_64 x86_64 GNU/Linux
[root@mynas-s5000xvn ~]# 

[mockbuild@buildserver SOURCES]$ cat config-4.3.4-x86_64 | grep XEN
CONFIG_XEN=y
CONFIG_XEN_DOM0=y
CONFIG_XEN_PVHVM=y
CONFIG_XEN_512GB=y
CONFIG_XEN_SAVE_RESTORE=y
CONFIG_XEN_DEBUG_FS=y
CONFIG_XEN_PVH=y
CONFIG_PCI_XEN=y
CONFIG_XEN_PCIDEV_FRONTEND=y
CONFIG_XEN_BLKDEV_FRONTEND=y
CONFIG_XEN_BLKDEV_BACKEND=y
CONFIG_XEN_SCSI_FRONTEND=m
CONFIG_NETXEN_NIC=m
CONFIG_XEN_NETDEV_FRONTEND=m
CONFIG_XEN_NETDEV_BACKEND=m
CONFIG_INPUT_XEN_KBDDEV_FRONTEND=y
CONFIG_HVC_XEN=y
CONFIG_HVC_XEN_FRONTEND=y
CONFIG_TCG_XEN=m
CONFIG_XEN_WDT=m
CONFIG_XEN_BALLOON=y
CONFIG_XEN_SELFBALLOONING=y
CONFIG_XEN_BALLOON_MEMORY_HOTPLUG=y
CONFIG_XEN_BALLOON_MEMORY_HOTPLUG_LIMIT=512
CONFIG_XEN_SCRUB_PAGES=y
CONFIG_XEN_DEV_EVTCHN=y
CONFIG_XEN_BACKEND=y
CONFIG_XENFS=y
CONFIG_XEN_COMPAT_XENFS=y
CONFIG_XEN_SYS_HYPERVISOR=y
CONFIG_XEN_XENBUS_FRONTEND=y
CONFIG_XEN_GNTDEV=y
CONFIG_XEN_GRANT_DEV_ALLOC=y
CONFIG_SWIOTLB_XEN=y
CONFIG_XEN_TMEM=m
CONFIG_XEN_PCIDEV_BACKEND=y
CONFIG_XEN_SCSI_BACKEND=m
CONFIG_XEN_PRIVCMD=y
CONFIG_XEN_ACPI_PROCESSOR=y
CONFIG_XEN_MCE_LOG=y
CONFIG_XEN_HAVE_PVMMU=y
CONFIG_XEN_EFI=y
CONFIG_XEN_AUTO_XLATE=y
CONFIG_XEN_ACPI=y
CONFIG_XEN_SYMS=y
CONFIG_XEN_HAVE_VPMU=y


I had the same issue with xen-4.4.1 in regards to xl & the cd-insert / cd-eject 
commands. The work around for me was to use the following:

        "/usr/sbin/xm block-configure $selectedVM file:$isoFile hdc:cdrom r"

Which would mount the ISO no issue in the host OS, however xm is depreciated 
and there is no equivalent command in xl - hence trying to get the correct 
command to actually work.

Best regards,

Alex

-----Original Message-----
From: Alex Braunegg [mailto:alex.braunegg@xxxxxxxxx] 
Sent: Tuesday, 9 February 2016 8:49 AM
To: 'Ian Campbell'; 'xen-devel@xxxxxxxxxxxxx'
Subject: RE: [Xen-devel] [BUG] libxl: error: 
libxl_device.c:301:libxl__device_disk_set_backend: no suitable backend for disk

Hi Ian,

Any update in looking at this issue?

Best regards,

Alex

-----Original Message-----
From: Alex Braunegg [mailto:alex.braunegg@xxxxxxxxx] 
Sent: Friday, 5 February 2016 6:19 AM
To: 'Ian Campbell'; 'xen-devel@xxxxxxxxxxxxx'
Subject: RE: [Xen-devel] [BUG] libxl: error: 
libxl_device.c:301:libxl__device_disk_set_backend: no suitable backend for disk

Hi Ian,

As per http://xenbits.xen.org/docs/4.6-testing/misc/xl-disk-configuration.txt 
the disk specification conforms to:

        disk = [ '/dev/vg/guest-volume,,hda', '/root/image.iso,,hdc,cdrom' ]

Is there any additional information you need to replicate this issue?

Best regards,

Alex


-----Original Message-----
From: Ian Campbell [mailto:ian.campbell@xxxxxxxxxx] 
Sent: Thursday, 4 February 2016 10:26 PM
To: Alex Braunegg; xen-devel@xxxxxxxxxxxxx
Subject: Re: [Xen-devel] [BUG] libxl: error: 
libxl_device.c:301:libxl__device_disk_set_backend: no suitable backend for disk

On Thu, 2016-02-04 at 10:53 +1100, Alex Braunegg wrote:
> 
> There was a thread on this in 2013
> (http://lists.xen.org/archives/html/xen-devel/2013-03/msg00806.html) however
> I have looked at the disk configuration, and there is no phy: / raw: / file:
> prefix to the disk specification.

Not sure what is going on but I just wanted to mention that phy: etc
prefixes are considered legacy. See http://xenbits.xen.org/docs/4.6-testing
/misc/xl-disk-configuration.txt for the actual syntax and how phy: is
mapped.

Ian.


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