tty device and tty subsystem - read syscall blocks

[otix]

Hi all,

I wrote a kernel module and implemented an tty device. Now I reached the testing phase and realized that the read syscall blocks permanently. Even if I write data to the device. I know that the subsystem block the read call if the buffer is empty, but it have to wake up if data occure. It doesn't.

Any ideas?

Best regards
Otix

[alf55]

Look at using the select syscall to detect when a read is needed due to data being present.

[otix]

I use the poll syscall to notify the userspace, but it have to work without such notification, haven't it?

[otix]

I got it.
I set the ICANON flag in the struct ktermios. For this reason the subsystem reads data only on the arrival of special characters (NL, EOL, EOF).
see man termios for details.

Best regards

Otix