FreeBSD blocks on BOCHS serial port

[Holger Kipp]

Hi Alex,

if serial interfaces are attached via USB, they might not be initialized correctly, because serial interface configuration happens before USB. I encountered this on physical hardware with 8-port USB to RS232.

Simple solution was to change settings using
# stty < /dev/cuaU0.init crtscts -ixon -ixoff
# stty < /dev/cuaU0.lock crtscts ixon ixoff
...
for all eight interfaces after boot completed.

I‘m not sure how serial interfaces are emulated with your VM-environment, though, but maybe your initialization process is just a bit too early?

Best regards,
Holger

Diplom-Mathematiker
Holger Kipp
Senior Consultant
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On 15. Aug 2018, at 13:08, Alexander Lochmann <alexander.lochmann at tu-dortmund.de<mailto:alexander.lochmann at tu-dortmund.de>> wrote:

I've to correct myself. It works if I activate the boot console
(console="vidconsole,comconsole").
If I change the mentioned line to console="vidconsole", neither writing
to /dev/ttyu0 nor reading from /dev/cuau1 works.
It seems that the FreeBSD loader initialize the serial ports in a
different way than the OS does.

- Alex

On 15.08.2018 12:46, Alexander Lochmann wrote:
Reading from /dev/cuau1 works. Thank you for your help!
However, I'm pretty sure I tried this device before. Nvm. It works.

- Alex

On 13.08.2018 22:49, Eugene Grosbein wrote:
14.08.2018 3:15, Alexander Lochmann wrote:

You should not rely on defaults and make sure you disable modem control/CD
either explicitly (using stty(1) etc.) or implicitly by switching to /dev/cuau0
instead of /dev/ttyu0. Flow control settings should match too, for both sides
of virtual port.
Thx. I cannot even run 'stty < /dev/ttyu1' to see the current settings.
It simply blocks...

Use /dev/ttyu1.init to see defaults and /dev/ttyu1.lock to set/show
locked defaults that cannot be changed without disabling a lock first.





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