Access denied to /dev/ttyUSB0

Gustavo Niemeyer gustavo.niemeyer at canonical.com
Wed Sep 7 23:34:14 UTC 2016


We've just been polishing this process in the last couple of weeks.

You just need to ask for a serial-port plug in your snap.

There's a step missing for that to work well, but that's on our end. We
need to expose serial-port slots in the gadget or core for serial-port-0
(S0) and serial-port-1 (S1) if those are available. In the near future,
these slots will show up automatically based on hotplug support.

Then, you can run something like:

snap connect yoursnap:serial-port ubuntu-core:serial-port-1



On Wed, Sep 7, 2016 at 8:29 PM, Enrique Hernández Bello <ehbello at gmail.com>
wrote:

> Hello,
>
> taking advantage of this thread, what is the right way to grant access
> of a /dev/ttyS0 to our snap in Ubuntu Core 16?
>
> Regards.
>
> 2016-09-07 15:26 GMT+01:00 Simon Fels <simon.fels at canonical.com>:
> > On 07.09.2016 15:05, Loïc Minier wrote:
> >> Hi,
> >>
> >> You need to use:
> >>
> >> plugs: [serial-port]
> >>
> >> In your snapcraft.yaml; then you also have to connect your snap to that
> >> interface manually as it's not autoconnected; check "snap interfaces" to
> >> see which plugs and slots are connected.
> >
> > That doesn't work anymore. There is no implicit slot for serial-port.
> > Right now the only option to get access to serial ports is via defining
> > a slot on a gadget snap with either a USB product/vendor id pair or a
> > absolute path to the serial node which then the snap can connect to and
> > it will only get access to that particular serial port.
> >
> > You can put something like
> >
> > slots:
> >   my-usb-serial-device:
> >     interface: serial-port
> >     product-id: 0x0
> >     vendor-id: 0x0
> >
> > into your gadget snap and then connect both the snap and gadget together
> > so your app gets access to that serial node.
> >
> > In a system where no gadget exists you currently don't get access to
> > serial nodes. We need to implement hotplut support to make this slots
> > automatically exported for those devices. Not sure for when this is on
> > the list.
> >
> > regards,
> > Simon
> >
> >>
> >>
> >> On Wed, Sep 7, 2016 at 4:00 PM, Jenny Murphy <
> jenny.murphy at episensor.com
> >> <mailto:jenny.murphy at episensor.com>> wrote:
> >>
> >>     Hi,
> >>      I solved the previous issue regarding the use of the RXTX java
> >>     library and the application is loading and running without errors.
> >>     However my java code isn't detecting the port, it should be able to
> >>     see /dev/ttyUSB0.
> >>
> >>     In the dmesg log I see the following errors :
> >>
> >>     [101043.875139] usb 1-2: new full-speed USB device number 7 using
> >>     xhci_hcd
> >>     [101044.006418] usb 1-2: New USB device found, idVendor=10c4,
> >>     idProduct=ea60
> >>     [101044.006441] usb 1-2: New USB device strings: Mfr=1, Product=2,
> >>     SerialNumber=3
> >>     [101044.006456] usb 1-2: Product: CP2102 USB to UART Bridge
> Controller
> >>     [101044.006470] usb 1-2: Manufacturer: Silicon Labs
> >>     [101044.006482] usb 1-2: SerialNumber: 0001
> >>     [101044.011589] cp210x 1-2:1.0: cp210x converter detected
> >>     [101044.012037] usb 1-2: cp210x converter now attached to ttyUSB0
> >>
> >>     [101098.191960] audit_printk_skb: 258 callbacks suppressed
> >>
> >>     [101098.191979] audit: type=1400 audit(1473254849.416:69078):
> >>     apparmor="DENIED" operation="open"
> >>     profile="gateway.sideload_main_IdNRFcRcGPGe" name="/dev/ttyUSB0"
> >>     pid=4875 comm="java" requested_mask="wr" denied_mask="wr" fsuid=0
> ouid=0
> >>
> >>
> >>     Is there anyway to solve this. I am working on a Ubuntu 15.04
> platform.
> >>
> >>     Thanks again.
> >>
> >>     --
> >>     *Jenny Murphy*
> >>     *EpiSensor, Georges Quay House, Georges Quay, Limerick, Ireland*
> >>     jenny.murphy at episensor.com <mailto:jenny.murphy at episensor.com>  t |
> >>     +353 (0) 61 512 511 <tel:%2B353%20%280%29%2061%20512%20511>  w |
> >>     http://www.episensor.com <http://www.episensor.com/>
> >>
> >>     --
> >>     Snapcraft mailing list
> >>     Snapcraft at lists.snapcraft.io <mailto:Snapcraft at lists.snapcraft.io>
> >>     Modify settings or unsubscribe at:
> >>     https://lists.ubuntu.com/mailman/listinfo/snapcraft
> >>     <https://lists.ubuntu.com/mailman/listinfo/snapcraft>
> >>
> >>
> >>
> >>
> >> --
> >> - Loïc
> >>
> >>
> >
> >
> > --
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>
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-- 
gustavo @ http://niemeyer.net
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