mdev

[Vladimir Dronnikov]

>>
>> -$MODALIAS=.+ 0:0 660 @modprobe "$MODALIAS"
>>
>> This line requires reading/parsing and should be put to matching for
>> any device. This is much slower than analyzing $MODALIAS in C. Do we
>> really need to slow things down?
>
> A) You are aware there are individual modules that take 30 seconds to
> initialize (some of the honking big scsi spin-up thingies)

No. What difference does it make to the tool?

>, and whether or
> not they block while doing so is up to the module author?  Putting "modprobe"
> and "Do we really need to slow things down?" in the same sentence is kind of
> amusing, really.

I meant what I wrote: getenv("MODALIAS") is faster than
reading/parsing a fair placeholder from the file. Wrong?

>
> B) The hotplug callback is not a fast path, it's an asynchronous process spawn
> that doesn't even need to serialize on other hotplug instances unless it
> wants to.

Great. Than we can exec modprobe, not fork/exec it :)

> Once upon a time mdev -s was the fast path.

I remember that. I don't remember though, was it my primary reason to
look at udev... :) But now it's definitely time to return.

>
> If I care enough I'll just dust off the unfinished mdev implementation in
> toybox, re-implement the "mmap" parsing, and write the wrapper script.

Maybe reuse makedevs?

Best regards,
--
Vladimir