I have a C++ app that receives data from an external board via serial over USB 2.0, written and tested on a system running Ubuntu 18.04. The same app does not work properly on a 20.04 system. The serial port is opened and some data comes through, but after receiving a few KB, the serial buffer no longer receives any data. I went back to the 18.04 system in case I had broken my app, but the same version works flawlessly on 18.04.
Has something changed between Ubuntu 18 and 20 regarding USB virtual serial ports? What can I change to get this app working on 20.04?
20.04 syslog:
Aug 16 16:01:52 ubuntu20 kernel: [ 1073.287531] usb 1-5: new full-speed USB device number 8 using xhci_hcd
Aug 16 16:01:52 ubuntu20 kernel: [ 1073.437195] usb 1-5: New USB device found, idVendor=058b, idProduct=0058, bcdDevice= 0.01
Aug 16 16:01:52 ubuntu20 kernel: [ 1073.437200] usb 1-5: New USB device strings: Mfr=1, Product=2, SerialNumber=0
Aug 16 16:01:52 ubuntu20 kernel: [ 1073.437202] usb 1-5: Product: IFX CDC
Aug 16 16:01:52 ubuntu20 kernel: [ 1073.437203] usb 1-5: Manufacturer: Infineon
Aug 16 16:01:52 ubuntu20 kernel: [ 1073.438679] cdc_acm 1-5:1.0: ttyACM1: USB ACM device
Aug 16 16:01:52 ubuntu20 mtp-probe: checking bus 1, device 8: "/sys/devices/pci0000:00/0000:00:14.0/usb1/1-5"
Aug 16 16:01:52 ubuntu20 mtp-probe: bus: 1, device: 8 was not an MTP device
Aug 16 16:01:52 ubuntu20 snapd[572]: hotplug.go:199: hotplug device add event ignored, enable experimental.hotplug
Aug 16 16:01:52 ubuntu20 mtp-probe: checking bus 1, device 8: "/sys/devices/pci0000:00/0000:00:14.0/usb1/1-5"
Aug 16 16:01:52 ubuntu20 mtp-probe: bus: 1, device: 8 was not an MTP device
18.04 syslog:
Aug 16 16:08:45 ubuntu18 kernel: [19713.493118] usb 1-5: new full-speed USB device number 12 using xhci_hcd
Aug 16 16:08:45 ubuntu18 kernel: [19713.633855] usb 1-5: New USB device found, idVendor=058b, idProduct=0058
Aug 16 16:08:45 ubuntu18 kernel: [19713.633861] usb 1-5: New USB device strings: Mfr=1, Product=2, SerialNumber=0
Aug 16 16:08:45 ubuntu18 kernel: [19713.633865] usb 1-5: Product: IFX CDC
Aug 16 16:08:45 ubuntu18 kernel: [19713.633868] usb 1-5: Manufacturer: Infineon
Aug 16 16:08:45 ubuntu18 kernel: [19713.634724] cdc_acm 1-5:1.0: ttyACM2: USB ACM device
Aug 16 16:08:45 ubuntu18 mtp-probe: checking bus 1, device 12: "/sys/devices/pci0000:00/0000:00:14.0/usb1/1-5"
Aug 16 16:08:45 ubuntu18 mtp-probe: bus: 1, device: 12 was not an MTP device
Aug 16 16:08:45 ubuntu18 snapd[893]: hotplug.go:199: hotplug device add event ignored, enable experimental.hotplug
