Re: [gentoo-user] Udev confusion: Rules for a mp3 player

Jc García <jyo.garcia@×××××.com> [14-06-28 19:48]:
> 2014-06-28 8:57 GMT-06:00  <meino.cramer@×××.de>:
> > Hi,
> >
> > For my mp3-player I want to write udev rules to give better names
> > to the according entries under /dev
> >
> > Problem is: Th eplayer has an internal flash, which only holds the firmware
> > (in my case) and a sd-card slot, in which you can insert a flash card
> > with music files.
> >
> > The internal memory has a partition directly on - say - sdb and the
> > sd-card in the slot is regulary formatted and represents itsself as
> > sdc and sdc1.
> >
> > With udevadm I determined the serial number of the device (to make it
> > unique) and the model ("Internal storage" and "SD card slot"), which
> > seems to make it easy to buit rules from.
> > The one and only reason for not being THAT happy is: The rules didn't work.
> >
> > Here:
> > http://www.reactivated.net/writing_udev_rules.html
> >
> > I read some instructions.
> > It is said that one should not combine elements of one device and more
> > than one parent.
> >
> > Is "device" meant as "the entry under /dev" or is it to be understand
> > as "the electric entity on my desktop (the player)".
> >
> > I want rules which also work, if another sdcard of a different size is
> > inserted into the player...
> >
> > How can I write rules to map the internal storage, the whole device
> > (aka /dev/sdc) of the sdcard (for example for reformatting reasons)
> > and the partition of the sdcard (aka /dev/sdc1), which work?
> >
> > To this email I have attached the gzipped outputs of the according
> > udevadm calls.
> >
> > Thank you very much for any help in advance!
> > Best regards,
> > mcc
> >
> > PS:
> > This is what I have tried and which does *NOT* work!
> > SUBSYSTEM=="block",ATTRS{model}=="Internal Storage",ATTRS{serial}=="1A8C518301403210B00000000",SYMLINK+="sansaclipzip_root"
> > SUBSYSTEM=="block",ATTRS{model}=="SD Card Slot    ",ATTR{partition}=="1", ATTRS{serial}=="1A8C518301403210B00000000", SYMLINK+="sansaclipzip_data_1"
> > SUBSYSTEM=="block",ATTRS{model}=="SD Card Slot    ",ATTRS{serial}=="1A8C518301403210B00000000", SYMLINK+="sansaclipzip_data"
> >
> >
> I'm not going to help you with your udev rules, but just point out, it
> seems to me you are going to a more complicated layer than you need
> to, if you just want personalized naming for your partitions under
> /dev (for using with scripts or something like that), I would suggest
> you to use the label feature, of the filesystems you are going to use
> for those blocks, this will cause udev to generate respective
> /dev/disk/by-label/* symlinks, altought I guess if you already know
> this if you are playing with udev rules.
>

...this would identify the sd-cards instead of the device, so I choose
to udev-rules instead of labels...

Best regards,
mcc