[RFC] Support for raw-ip only modems in libqmi/qmicli/qmi-network

[Bjørn Mork]

Aleksander Morgado <aleksander at aleksander.es> writes:
> On Sat, Jan 2, 2016 at 11:14 PM, Bjørn Mork <bjorn at mork.no> wrote:
>> This also made me realize one flaw in the kernel side solution:
>>
>>  bjorn at nemi:~$ qmicli -d /dev/cdc-wdm0  --set-expected-data-format=raw-ip
>>  error: cannot set expected data format: Expected data format not updated properly: Failed to open file '/sys/class/net/wwan0/qmi/raw_ip' for R/W: Permission denied
>>
>>
>> The sysfs file and the cdc-wdmX character device permissions are in no
>> way connected, but I guess that will be somewhat confusing.  I really
>> haven't thought enough (or much at all..) on how this should work.  But
>> I guess it can (and should?) be left for userspace to figure out?
>
> In libqmi we can ship udev rules to change ownership/group of the
> cdc-wdm devices. Are we able to do the same with the sysfs files? Or
> is there some restriction on what we can do with those files?

Good questions.  I don't know, and I cannot find any good answers
either.

You can obviously change the mode and owner as you like, but there are
no good examples of udev rules doing such stuff. Which is suspicious.
You would think this was a generic problem. And the possibility isn't
mentioned in Documentation/filesystems/sysfs.txt where I would have
expected it.  So who knows if that is supported or just happens to work?


Bjørn