[catalin.crenguta]

Hello,

I'm using usb_modeswitch (2.2.6, db 2015-11-01) on a Yocto core-image-minimal and I'm having trouble with automatic switching.
The modeswitch works if I do it manually (usb_modeswitch -v 12d1 -p 1f16 -J) but it won't work with the udev scripts.
I have tried to locate the problem but I'm stuck, and the log is empty.
I can tell for sure that udev is invoking /lib/udev/usb_modeswitch and that in turn invokes usb_modeswitch_dispatcher --switch-mode 2-1.2/2-1.2:1.0 and nothing happens afterwards.
If I run usb_modeswitch_dispatcher --switch-mode 2-1.2/2-1.2:1.0 , I get the following output:
error waiting for process to exit: child process lost (is SIGCHLD ignored or trapped?)
while executing
"exec echo "\nUSB_ModeSwitch log from [clock format [clock seconds]]" >/var/log/usb_modeswitch_$device"
invoked from within
"if [string length $loginit] {
exec echo "\nUSB_ModeSwitch log from [clock format [clock seconds]]" >/var/log/usb_modeswitch_$device
exec echo "$lo..."
invoked from within
"if $flags(logwrite) {
if [string length $loginit] {
exec echo "\nUSB_ModeSwitch log from [clock format [clock seconds]]" >/var/log/usb_modeswitch_$..."
(procedure "Log" line 7)
invoked from within
"Log "\n----------------\nUSB values from sysfs:""
invoked from within
"if $flags(logging) {
Log "\n----------------\nUSB values from sysfs:"
foreach attr {manufacturer product serial} {
Log " $attr\t$usb($attr)"
}
..."
(procedure "Main" line 133)
invoked from within
"Main $argv $argc"
(file "/usr/sbin/usb_modeswitch_dispatcher" line 1196)

If I disable logging, the stacktrace is easier to read:
usb_modeswitch_dispatcher --switch-mode 2-1.2/2-1.2:1.0
error waiting for process to exit: child process lost (is SIGCHLD ignored or trapped?)
while executing
"exec cat /proc/version"
(procedure "Main" line 157)
invoked from within
"Main $argv $argc"
(file "/usr/sbin/usb_modeswitch_dispatcher" line 1196)

Executing exec cat /proc/version works just fine with the following output:
Linux version 4.3.0-test3 (dev@development.localdomain) (gcc version 5.2.0 (GCC) ) #1 Fri Nov 13 14:09:25 EET 2015

Any ideas?

Any help is appreciated!
Best regards!

[Josh]

Good analysis, the problem is obvious.

Can you check where the "cat" and "echo" programs are sitting in your system? A simple "which cat" should do.

I suspect they are not in a standard path.

[catalin.crenguta]

Hello Josh,
Unfortunately that is not the problem, they are in the right place.
I have tried poking with the tclsh and it seems that exec always fails, even with the full path of the binary, and returns the "error waiting for process to exit: child process lost (is SIGCHLD ignored or trapped?)" error.
I have no idea what is wrong with the tclsh.
Any ideas? Or replacements for that TCL script?

Best regards!

[Josh]

Do you have a special tcl version installed?

In any case, you can try to link the dispatcher with an embedded tcl interpreter. I think the command was "make static" in the usb_modeswitch source folder.