Messages in this thread | | | Date | Wed, 1 May 2002 09:45:01 -0700 (PDT) | From | David Dyck <> | Subject | Re: changes between 2.2.20 and 2.4.x 'broke' select() from detecting input characters in my serial /dev/ttyS0 program |
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On Wed, 1 May 2002 at 11:03 -0400, Stuart MacDonald <stuartm@connecttech.co...:
> CREAD handling was changed to be correct; recently, but I don't know > exactly when. The 2.4 vs 2.2 difference sounds about right though. > Previously CREAD had been incorrectly handled by the driver and hadn't > been changed because some apps would break. Now data is correctly > ignored on receive when CREAD is off. > > When you talk about the "O_WRONLY channel" and the "O_RDONLY channel" > you're not actually referring to separate things. Each serial port is > represented in the kernel as one entity that may be opened different > ways, possibly multiple times. > > When you turn off CREAD in your write side, you turn off CREAD for the > whole port, including the read only side. This is not a bug in the > driver.
Thanks for your response. (thanks also the the other folks that responded). It makes sense to me that 2 open calls to the same "/dev/ttyS0" should map to the same driver and kernel structure, so there is only one place that CREAD effects.
To bad that the 2.2 code was in error, but I can work around with that.
David
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