Zynq: Reading from stdin returns immediately

Jan.Sommer at dlr.de Jan.Sommer at dlr.de
Tue Feb 9 09:57:46 UTC 2021


I tried to read data from stdin via scanf in RTEMS5.1 for some user input for a Zynq based board, but it returns immediately with 0.
Also fscanf, read or fgetc do not block and return immediately. The flags for stdin show that the O_NONBLOCK flag is not set.
I tried to check with the termios application from the testsuite since it uses those functions as well.
There seems to be the same behavior. At least I only see the test begin and end markers, but never the
"Press any key to check the termios input capabilities (20s remaining)" as mentioned in the example output.
The test also finishes immediately.

I also found this thread from Joel, which might be related, but I am not sure: https://lists.rtems.org/pipermail/devel/2020-November/063533.html

The rtems_shell seem to work however. At least there the input is correctly received and processed.
Does someone have a hint where I would need to look? I will try with the current master as well, but don't expect that this will change much.

Best regards,


Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)
German Aerospace Center
Institute for Software Technology | Software for Space Systems and Interactive Visualization | Lilienthalplatz 7 | 38108 Braunschweig | Germany

Jan Sommer
Telephone +49 531 295-2494 | Telefax 0531 295-2767 | jan.sommer at dlr.de

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