On 11/20/18 6:42 PM, Johan Hovold wrote:
On Tue, Nov 20, 2018 at 01:17:34PM +0200, Jarkko Nikula wrote:
Hi
I'm using PL2303 based USB serial adapter for the kernel and getty
serial console. I noticed getty console stopped working in v4.18 and
bisected this into commit 7041d9c3f01b ("USB: serial: pl2303: add
support for tx xon/xoff flow control").
Serial console works up to somewhere after when getty service starts. I
can sometimes see on the serial console that getty was started but not
always. After that there is no messages printed from the kernel or
userspace.
[ OK ] Started Getty on tty1.
[ OK ] Started Serial Getty on ttyUSB0.
[ OK ] Reached target Login Prompts.
[ OK ] Started Login Service.
IXON is enabled by default, and it sounds like flow could have been
stopped. What happens if you send a start character (ctrl-q) on the
console?
Nothing, it remains silent.
And what if you disable the getty? Does the port work then?
systemctl disable serial-getty@ttyUSB0.service followed by reboot and I
can see everything what systemd is outputting there as well as what is
dumped to /dev/kmsg so it looks getty started by systemd changes or
triggers the port reconfiguration.
Does the IXON behavior differ from 8250 based serial consoles? I have
the same user space and 8250 based serial consoles work fine.
--
Jarkko
