I am using the trial version of Lightburn and I am experiencing issues with Lightburn hanging at startup. The issue is virtually identical to that reported by @payala earlier this year – that thread was automatically closed and there seems to be no way of re-opening it.
I am using Ubuntu 18.10 on a laptop with no USB devices connected (not connected to the laser yet). What I am experiencing is that the first time Lightburn is opened after system reboot, it opens fine. On each subsequent invocation, it hangs for just over 60 seconds before showing the main window.
The problem seems to be related to Lightburn trying to access /dev/ttyS0. I have investigated this a little using strace and have discovered the following. On the first invocation the system calls are as follows:
access("/sys/devices/platform/serial8250/uevent", F_OK) = 0
readlinkat(AT_FDCWD, "/sys/devices/platform/serial8250/driver", "../../../bus/platform/drivers/se"..., 99) = 40
openat(AT_FDCWD, "/dev/ttyS0", O_RDWR|O_NOCTTY|O_NONBLOCK|O_CLOEXEC) = -1 EBUSY (Device or resource busy)
openat(AT_FDCWD, "/", O_RDONLY|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 20
openat(20, "sys", O_RDONLY|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 21
However, on each subsequent invocation the system calls look like this:
access("/sys/devices/platform/serial8250/uevent", F_OK) = 0
readlinkat(AT_FDCWD, "/sys/devices/platform/serial8250/driver", "../../../bus/platform/drivers/se"..., 99) = 40
openat(AT_FDCWD, "/dev/ttyS0", O_RDWR|O_NOCTTY|O_NONBLOCK|O_CLOEXEC) = 18
ioctl(18, TIOCGSERIAL, 0x7ffc51e15b60) = 0
close(18) = 0
readlinkat(AT_FDCWD, "/sys/devices/platform/serial8250/tty/ttyS0/subsystem", "../../../../../class/tty", 99) = 24
The system hangs for about 30s during the openat() call and then again for another 30s at the close() call, after which Lightburn reports ‘Port open succeeded’ on stdout.
Hopefully this is enough to help you.
Regards,
Chris