Use a specific device ?

[Jean-Christian de Rivaz]

Le 10. 06. 15 16:36, Dan Williams a écrit :
> On Tue, 2015-06-09 at 21:22 +0200, Jean-Christian de Rivaz wrote:
>>
>> This black list, grey list, and white list system is a mess and have to
>> die. No other application do that way because this is completely against
>> the common sense. It like saying that by default every house is your and
>> that the others have to send to you a list of the houses where you must
>> not enter without invitation. All others applications use udev to select
> It's a simple numeric calculation.  The number of items in the whitelist
> would be far, far greater than the number of items in the blacklist.
> You also may not realize how many modems are released each year, how
> many manufacturers make them, and how many models/variants there are...
>
> The number of non-modems that are driven by the same drivers as modems
> (eg, cdc-acm, pl2xxx, ftdio) is much, much smaller than the number of
> modems driven by those same drivers, and so we blacklist them instead.
>
> Again, we will respond quickly to new requests for blacklist/greylist to
> ensure that ModemManager doesn't probe UPS or whatever.

The various black/grey/white lists of ModemManager are together already 
one of the top biggest udev rules list, and there are very incomplete 
because there is a lot of industrial products that still use serial 
ports for specific command and control. The first reason why the list is 
not growing is that only a few peoples know that there need to blacklist 
there non modem products. I completely disagree about the argument that 
a white list will be too big. There is not so much modem manufacturers 
and each of them don't even release a new product range per year. The 
40-usb_modeswitch.rules required by some modems is not so big either. 
Really this is not so different to the gphoto2 or sane udev rules lists.

But most important is to understand that the current ModemManager is 
abusing the udev concept and confusing the users. Are you really serious 
when you ask a random people with a new UPS product to add a new udev 
rule to the ModemManager project? I think you are so focused on 
defending the current ModemManager abomination that you fail to see the 
problem from the point of view of a common user. The length of a white 
list is not an excuse to not fix the problem.

>> the appropriate device, not to reject inappropriate device. This is an
>> abuse of the udev technical capabilities. Yes there exists a few other
>> udev blacklist rules, but there are clearly for exceptional cases.
>> ModemManager try to make the abuse a general concept and this is bad.
>> Try to think I bit more globally and imagine the mess if every
>> applications do that way. Imagine the /lib/udev/rules.d/ with only black
>> list rules for every possible types of devices... Can you seriously
>> thing that distributions and users will be happy with a such chaotic system?
>>
>>   From the current /lib/udev/rules.d there is already 16 files for
>> ModemManager only and 5 of them are just for black/grey/white list. This
>> is ridiculous. The ID_MM_BLACKLIST idea was terribly wrong. I hope the
>> ModemManager will understand that some transition would be an advantage
>> for everyone.
> I don't agree.  A whitelist would have two consequences: (a) many, many
> modems would not work out of the box, and (b) we would be spending much
> more time updating already-out-of-date whitelists and kernel drivers
> than we would adding features and capabilities to ModemManager.
>

As I have say before, please let the choice to the distributions and to 
the users. I never asked to completely remove the auto probing feature 
of ModemManager, I ask to have more control on it and to make it not the 
only possible ModemManager mode of operation. A transition plan could be 
to still auto probe by default udev rule but with a way that allow 
reporting the modem vendor/product id if he is not already in the list. 
This will solve (a). For (b), my point of view is exactly the opposite: 
if ModemManager will allow to select the features set of a modem from a 
udev rule using variable, then advanced users can try to enable more 
features on a new modem by just writing a udev rule. Very powerful and 
without having to compile a new code.

Jean-Christian