Public bug reported:
After the upgrade to Kubuntu 10.10 I was not able connect to my buspirate (FTDI
USB -> serial). Minicom reported:
minicom: cannot open /dev/buspirate: Device or resource busy
uname -a : Linux lorelei 2.6.35-22-generic #34-Ubuntu SMP Sun Oct 10
09:26:05 UTC 2010 x86_64 GNU/Linux
This was working fine before the upgrade. At that time I had the following udev
rule: 98-buspirate.rules
UBSYSTEM=="tty", ATTRS{serial}=="A7004DMs", GROUP="users", MODE="0660",
SYMLINK+="buspirate"
I thought it could have something to do with the rule so I removed it and
reloaded the udev rules:
sudo udevadm control --reload-rules
Then again I could acces /dev/ttyUSB0 as normal user.
Today after a reboot I wanted to access my buspirate through minicom (udev rule
removed) and could not access /dev/ttyUSB0:
minicom: cannot open /dev/ttyUSB0: Device or resource busy
I checked the permissions:
p...@lorelei:~$ ls -al /dev/ttyUSB0
crw-rw---- 1 root dialout 188, 0 2010-10-18 20:52 /dev/ttyUSB0
Group membership:
p...@lorelei:~$ groups
ping adm dialout cdrom plugdev users lpadmin admin sambashare vboxusers
Even added myself to the uucp group but to nothing changed. Tried
reloading the ftdi_sio kernel module but didn't help.
dmesg entries look normal I think:
[ 7795.737299] ftdi_sio ttyUSB0: FTDI USB Serial Device converter now
disconnected from ttyUSB0
[ 7795.737309] ftdi_sio 6-2:1.0: device disconnected
[ 7798.963590] usb 6-2: new full speed USB device using uhci_hcd and address 8
[ 7799.178150] ftdi_sio 6-2:1.0: FTDI USB Serial Device converter detected
[ 7799.178188] usb 6-2: Detected FT232RL
[ 7799.178192] usb 6-2: Number of endpoints 2
[ 7799.178196] usb 6-2: Endpoint 1 MaxPacketSize 64
[ 7799.178199] usb 6-2: Endpoint 2 MaxPacketSize 64
[ 7799.178203] usb 6-2: Setting MaxPacketSize 64
[ 7799.179162] usb 6-2: FTDI USB Serial Device converter now attached to ttyUSB0
I did an strace of minicom to see if I got any wiser:
....
stat("/var/lock", {st_mode=S_IFDIR|S_ISVTX|0777, st_size=40, ...}) = 0
open("/var/lock/LCK..ttyUSB0", O_RDONLY) = -1 ENOENT (No such file or directory)
umask(022) = 022
open("/var/lock/LCK..ttyUSB0", O_WRONLY|O_CREAT|O_EXCL, 0666) = 3
getpid() = 10590
write(3, " 10590\n", 11) = 11
close(3) = 0
umask(022) = 022
rt_sigaction(SIGALRM, {0x4199f0, [ALRM], SA_RESTORER|SA_RESTART,
0x7f42a5850c20}, {SIG_DFL, [], 0}, 8) = 0
alarm(4) = 0
open("/dev/ttyUSB0", O_RDWR|O_NOCTTY|O_NONBLOCK) = -1 EBUSY (Device or resource
busy)
alarm(0) = 4
rt_sigaction(SIGALRM, {SIG_IGN, [ALRM], SA_RESTORER|SA_RESTART,
0x7f42a5850c20}, {0x4199f0, [ALRM], SA_RESTORER|SA_RESTART, 0x7f42a5850c20}, 8)
= 0
....
Permissions of /var/lock can't be the cause...
Using sudo I can access the buspirate, but I want to run my programs as
a regular user...
I did notice that connecting through minicom to /dev/ttyS0 with the same
permissions is successful.
** Affects: ubuntu
Importance: Undecided
Status: New
--
ftdi usb serial node only accessible by root
https://bugs.launchpad.net/bugs/662881
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