Comment 26 for bug 661321

I noticed this bug today, after upgrading to 12.04.1.
It seems Michael Stevens (#12) is right and it's a change on the kernel semantics, because to me this happens with regular serial ports (I have a serial port PCI card to add 2 more ports to the machine).

This is a serious regression on the kernel behavior. Unconfigured serial ports now freeze when opened, instead of just failing, meaning many old programs need to be fixed to work with the new behavior.

And this is not so trivial as many many think. I work with a lot of serial, paralel and it's USB equivalent devices (USB serial, usblp and raw USB) and there are a lot of device quirks in there. There are devices that simply don't work with O_NONBLOCK and many serial ones use 3 wire serial cables, with no flow control and no shunts -- and modern techs don't knows how to make cables anymore when it requires soldering.

To me this is chaos in support calls...