Re: [Owfs-developers] Issues with FTDI based USB-Serial dongle & DS2480B

[Johan S. <jo...@st...>]

On 9/30/14 15:50 , Stefano Miccoli wrote:
>
> On 30 Sep 2014, at 08:32, Johan Ström <jo...@st... 
> <mailto:jo...@st...>> wrote:
>
>> Hi all,
>>
>> picking this up again. Lets summarize the main points:
>>
>> * auto-detection can only be relied on for certain pure USB devices
>> * auto-detection can not be relied on when "standard" serial bridge 
>> chips are used
>> * if we can resolve /dev/ttyUSB0 to a particular USB device, we can 
>> potentially select a smarter (i.e. improved FTDI) code path instead 
>> of regular read/write from the tty device.
>> * /dev/ttyUSB0 is not stable, unless explicit devd setup is done.
>> * this makes alterantive OWFS device addressing interesting, by 
>> specifying USB serial. this would avoid devd all together.
>
> excellent recap. Let me add another remark.
>
> It seems that Debian, and most of the developers like to run owserver 
> and companion programs as root. Personally I do not like this: on 
> production systems I run owserver without root privileges, so 
> udev/devd is still necessary to set appropriate permissions to /dev files.

Good catch, that would still be required...
Imo, running as root should be discouraged in all cases, even for 
developers.
>
> Unfortunately this means that with serial emulators some manual setup 
> is needed: inspecting syslog files, noting the device serial number, 
> modifying the udev/devd script. Alternatively owserver and family 
> should drop root privileges after startup.
Using a regular TTY name should of course always work. But yes, to not 
run as root it would be required.
Not sure about dropping root, owfs usually closes/opens the devices if 
it looses track of the state, in order to reset. I guess that would not 
work.

>
> Stefano
>
>
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