Bug 461293

Try adding this in the /etc/modprobe.conf file:

alias pci:v00008086d00007010sv00005853sd00000001bc*sc*i* xen-vbd


and see if that makes xvd's get setup/connected to driver(s).

- Don

Note: a fully updated 4.6 system will become a 4.7 kernel, thus the same issue due to it being the same kernel.

in 4.7, the built-in xenpvhvm drivers are being used.

 

Added requested alias.  The driver did not load.  Saw the following in /var/log/messages corresponding to boot with alias.


Sep  5 16:04:07 ra-vm8 kernel: XENBUS: Device with no driver: device/vif/0
Sep  5 16:04:07 ra-vm8 kernel: XENBUS: Device with no driver: device/vbd/768
Sep  5 16:04:07 ra-vm8 kernel: XENBUS: Device with no driver: device/vbd/5171



In original I tried "alias scsi_adapter xen-vbd".   I should have tried 
alias scsi_hostadapter xen-vbd.  When this is done, it is listed in a lsmod, however the device is still not configured.

the messages in #4 always occur -- they are generated by xenbus_probe(),
before a driver match is found for vif/vbd devices.
note, how your vnif is configured, even though the XENBUS messages say no driver for vif/0.

Can you try a sequence of block-attach, block-detach, to see if they work ?
eg:
xm block-attach ra-vm8 tap:aio://var/lib/xen/images/ra-vm8_usr.dsk /dev/xvdb r
xm block-list ra-vm8     --> to get xen-generated number to pass in next line
xm block-detach ra-vm8 51728

after the xm block-attach, you should be able to do the following
(in the guest) and see an xvd listed:
   kudzu -p -c HD

root@renoir:/etc/sysconfig
> xm block-attach ra-vm8 tap:aio:/var/lib/xen/images/extra_file /dev/xvdb r

root@renoir:/etc/sysconfig
> xm block-list ra-vm8
Vdev  BE handle state evt-ch ring-ref BE-path
768    0    0     1      -1     -1    /local/domain/0/backend/vbd/89/768  
51728    0    0     4      10     770   /local/domain/0/backend/tap/89/51728  

root@renoir:/etc/sysconfig
>


On guest --

root@ra-vm8:~
> kudzu -p -c HD
-
class: HD
bus: IDE
detached: 0
device: hda
driver: ignore
desc: "QEMU HARDDISK"
physical: 16383/16/63
logical: 16383/255/63
-
class: HD
bus: XEN
detached: 0
device: xvda
driver: xenblk
desc: "Xen Virtual Block Device"

root@ra-vm8:~
> ls /sys/block
dm-0  hda    loop1  loop3  loop5  loop7  ram0  ram10  ram12  ram14  ram2  ram4  ram6  ram8  xvdb
dm-1  loop0  loop2  loop4  loop6  md0    ram1  ram11  ram13  ram15  ram3  ram5  ram7  ram9

root@ra-vm8:~
> 



Host ---

root@renoir:/etc/sysconfig
> xm block-detach ra-vm8 51728

root@renoir:/etc/sysconfig
> 


Guest ----

root@ra-vm8:~
> ls /sys/block
dm-0  hda    loop1  loop3  loop5  loop7  ram0  ram10  ram12  ram14  ram2  ram4  ram6  ram8
dm-1  loop0  loop2  loop4  loop6  md0    ram1  ram11  ram13  ram15  ram3  ram5  ram7  ram9

root@ra-vm8:~
> 



~~~

I did a little experimenting

The config file has:
disk = [ "phy:/dev/RenoirVirtVG/ra-vm8-RHEL47fv2-vol,hda,w", "tap:aio:/var/lib/xen/images/prealloc_file,xvda,w" ]

On a startup this device is not seen.

I can get a xm block-attach device to be seen if  scsi_hostadapter is in the modprobe.com.  The long alias did not seem to have much effect.

The raw source of this problem is that the same loadable modules didn't exist btwn a rhel4.6+kmod-xenpv system and rhel4.7.

the patch posted for bz474667 resolves this issue;
similar problem occurred in rhel5 & was fixed there in a separate bz.

marking as duplicate.

*** This bug has been marked as a duplicate of bug 474667 ***