Linux domU only works with xen_platform_pci=0 ?

[Nathan Friess]

On 2018-05-19 02:02 AM, Roger Pau Monné wrote:
> On Thu, May 17, 2018 at 06:10:15PM -0600, Nathan Friess wrote:
>> I tried the patch on and I my Linux domU did was not able to complete the
>> attachment to the FreeBSD backend.  I applied the patch to the 11-RELEASE
>> kernel. (I couldn't get 11-STABLE to compile.)
>>
>> With xen_platform_pci=0 the frontend and backend vbds were both stuck in
>> state 1.  With xen_platform_pci=1 the frontend was in state 1 and backend in
>> state 3.
> 
> Thanks for the testing! I however think you had some issue applying
> the patch or building/installing the kernel, with the attached patch
> the backend should never go into state 3.
> 
> Can you confirm that you have the patch correctly applied to the
> kernel you are running?
> 
> And if so, can you try to debug why the backend goes into state 3?
> 
> FWIW, the patch works fine for me and I've been able to boot Debian
> and Alpine Linux guests without having to add xen_platform_pci=0.
> 
> Thanks, Roger.
> 

Sorry, I don't which run I was looking at there.  Here is the order of 
events.  There are two zvols exposed to the domU, 
/dev/zvol/zroot/vmachines/smyth/rootfs and .../swap, so the messages are 
interspersed between the two.

xbb(xbb_attach:3738): Attaching to backend/vbd/10/51713
xbb(xbb_attach:3802): Attach done, set state InitWait
xbb(xbb_attach_disk:3612): Enter xbb_attach_disk
xbb(xbb_attach_disk:3620):   Read physical-device-path failed
xbb(xbb_frontend_changed:3918): frontend_state=Initialising, 
xbb_state=InitWait
xbb(xbb_attach:3738): Attaching to backend/vbd/10/51714
xbb(xbb_attach:3802): Attach done, set state InitWait
xbb(xbb_attach_disk:3612): Enter xbb_attach_disk
xbb(xbb_attach_disk:3620):   Read physical-device-path failed
xbb(xbb_frontend_changed:3918): frontend_state=Initialising, 
xbb_state=InitWait
(Shell script) Start block script /local/domain/9/backend/vbd/10/51714 add
(Shell script) Start block script /local/domain/9/backend/vbd/10/51713 add
[1] xbb(xbb_frontend_changed:3918): frontend_state=Initialised, 
xbb_state=InitWait
xbb(xbb_connect:3316): Enter xbb_connect: hotplug=0, get_state=2, 
collect_frontend=0
[1] xbb(xbb_frontend_changed:3918): frontend_state=Initialised, 
xbb_state=InitWait
xbb(xbb_connect:3316): Enter xbb_connect: hotplug=0, get_state=2, 
collect_frontend=0
(Shell script) Write /dev/zvol/zroot/vmachines/smyth/rootfs to 
/local/domain/9/backend/vbd/10/51713/physical-device-path
xbb(xbb_attach_disk:3612): Enter xbb_attach_disk
xbb(xbb_open_backend:2687): opening 
dev=/dev/zvol/zroot/vmachines/smyth/rootfs
xbb(xbb_open_backend:2757): opened 
dev=/dev/zvol/zroot/vmachines/smyth/rootfs sector_size=512 
media_size=21474836480
xbb(xbb_attach_disk:3718): Set hotplug done, attach_disk done
(Shell script) Write /dev/zvol/zroot/vmachines/smyth/swap to 
/local/domain/9/backend/vbd/10/51714/physical-device-path
xbb(xbb_attach_disk:3612): Enter xbb_attach_disk
xbb(xbb_open_backend:2687): opening dev=/dev/zvol/zroot/vmachines/smyth/swap
xbb(xbb_open_backend:2757): opened 
dev=/dev/zvol/zroot/vmachines/smyth/swap sector_size=512 
media_size=2147483648
xbb(xbb_attach_disk:3718): Set hotplug done, attach_disk done

... is stuck here...

At [1] the frontend has transitioned to Initialised but the block script 
has not completed yet so hotplug_done is 0 and the notification about 
the frontend status change is lost.  Calling xbb_connect at the end of 
xbb_attach_disk like in the attached patch will catch this case. Now 
with your recent change and the attached file I can use Linux domUs 
successfully!


On a related note, did these patches ever make it into 11-stable?  I 
don't see them at svn.freebsd.org/base/stable/11 but I may have missed 
something.

https://lists.freebsd.org/pipermail/freebsd-xen/2016-December/002918.html

There were 4 patches, the third one being required for xl devd to 
trigger block scripts.  I have been using them as well for over a year 
with no issues:

https://lists.freebsd.org/pipermail/freebsd-xen/2016-December/002918.html

Thanks,

Nathan
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