Re: [PATCH] xserver-nodm-init: Respawn service in case of failure

[Nicolas Dechesne <nicolas.dechesne@linaro.org>]

On Thu, Apr 12, 2018 at 5:55 PM, Khem Raj <raj.khem@gmail.com> wrote:
> On 4/10/18 12:48 PM, Nicolas Dechesne wrote:
>> On Tue, Apr 10, 2018 at 1:20 PM, Ramon Fried <ramon.fried@linaro.org> wrote:
>>> From: Ramon Fried <rfried@codeaurora.org>
>>>
>>> It appears that sometimes xserver-nodm.service is starting before
>>> display driver finished loading causing the following failure in
>>> Xorg log:
>>> (EE) open /dev/dri/card0: No such file or directory
>>>
>>> The introduced by this patch is to restart the service,
>>> hopefully the display driver will finish loading.
>>>
>>> Signed-off-by: Ramon Fried <rfried@codeaurora.org>
>>
>> we are seeing this issue on Dragonboard with meta-qcom BSP, where all
>> drivers needed for display/gpu are modules, so the display
>> initialization comes up 'late' in the boot. I had a discussion with
>> some upstream gnome folks who indicated that a similar race can be
>> observed on any hardware, it is not uncommon, and that's why they use
>> Restart=always in gdm.service as well, so that it keep trying until
>> the display comes up.
>>
>> it sounds reasonable change to me.
>
> Restarting service always seems like a workaround here. I wonder if the
> kernel modules tied themselves to systemd-modules-load.service then the
> dependencies should
> sort themselves out. Alternatively we can also create a dependency on
> device being made available.

I would tend to agree that restart is a workaround, but since
gdm.service does that too, i thought it wasn't so bad..

we tried with a udev rule like that:

ACTION=="add", SUBSYSTEM=="drm", KERNEL=="card0", TAG+="systemd",
ENV{SYSTEMD_WANTS}+="xserver-nodm.service"

and it works well too.

between the two, i still prefer the restart=always..

>
>>
>> Reviewed-by: Nicolas Dechesne <nicolas.dechesne@linaro.org>
>>
>>> ---
>>>  .../x11-common/xserver-nodm-init/xserver-nodm.service.in                 | 1 +
>>>  1 file changed, 1 insertion(+)
>>>
>>> diff --git a/meta/recipes-graphics/x11-common/xserver-nodm-init/xserver-nodm.service.in b/meta/recipes-graphics/x11-common/xserver-nodm-init/xserver-nodm.service.in
>>> index 324a26f549..87dc4f8fcd 100644
>>> --- a/meta/recipes-graphics/x11-common/xserver-nodm-init/xserver-nodm.service.in
>>> +++ b/meta/recipes-graphics/x11-common/xserver-nodm-init/xserver-nodm.service.in
>>> @@ -5,6 +5,7 @@ Description=Xserver startup without a display manager
>>>  EnvironmentFile=/etc/default/xserver-nodm
>>>  User=@USER@
>>>  ExecStart=/etc/xserver-nodm/Xserver
>>> +Restart=always
>>>
>>>  [Install]
>>>  Alias=display-manager.service
>>> --
>>> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
>>> a Linux Foundation Collaborative Project
>>>
>