[OpenWrt-Devel] [PATCH] procd: remove /dev filter on uevents

[John Crispin]

On 07/12/2018 11:11, Hattink, Tjalling wrote:
>> -----Original Message-----
>> From: openwrt-devel [mailto:openwrt-devel-bounces at lists.openwrt.org]
>> On Behalf Of Jo-Philipp Wich
>> Sent: Friday, December 7, 2018 10:51
>> To: openwrt-devel at lists.openwrt.org
>> Subject: Re: [OpenWrt-Devel] [PATCH] procd: remove /dev filter on uevents
>>
>> Hi,
>>
>> I had a brief discussion with John on this matter and was being told that the
>> reason for this filter was to optimize boot time.
>>
>> When we remove the /dev filter, boot time will increase considerably on
>> lower end devices due to the resulting hotplug-call overhead of the huge
>> volume of additional uevents.
>>
>> A better approach here would be to selectively whitelist uevents based on
>> subsystem or similar attributes, e.g. `DEVTYPE=usb_device`.
>>
>> ~ Jo
> I can imagine that this would increase boot times on low end devices.
> Looking at the commit message introducing the filter it seems to
> cut down the amount of events by half.
>
> How about adding a compile option to procd that enables/disables this
> filter. So by default this filter is enabled, but using a makemenu option
> in the procd configuration (similar as "Mount /tmp using zram" option)
> you would be able to disable the filter for high-end boards that require
> it. This would be fairly easy to implement.
>
> Best regards,
> Tjaling Hattink

Hi,

I actually have a rather strong opinion on this one and would prefer to 
hardcode uevents that we want to opt-in as Jo suggested. compile time 
options do look nice, but we have a trizillion of them already and they 
per default are not enabled in binary releases making them virtually 
useless to anyone that was not involved in adding them to the tree.

     John





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