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termios XON/XOFF



On May 2, 2007, at 1:39 PM, Aaron J. Grier wrote:

> On Wed, May 02, 2007 at 12:01:15PM -0500, Eric Norum wrote:
>> <Controversial>
>> My feeling is that the termios code is already too complicated and
>> that all the code to support XON/XOFF flow control should be optional
>> or removed.
>> Does anyone really use this antiquated and unreliable  means of flow
>> control any more?
>> I'd be happy with leaving flow control up to the hardware (RTS/CTS)
>> and dropping all references to flow control from the generic termios
>> code.
>> /<Controversial>
>
> RTS/CTS is still going to affect termios even if the heavy lifting is
> being managed in the device driver, and at the very least the knobs  
> for
> enabling/disabling it have to be exported.  if RTS/CTS isn't  
> managed by
> hardware, that leaves termios to deal with it.

I see that I wasn't clear enough in my rant above.   I do, in fact,  
suggest that flow control be limited not only to RTS/CTS, but further  
to hardware which supports it.  Then the only vestige of flow control  
support left in the generic termios code is that which passes the  
enable/disable request down to the individual drivers.

Like I said, "controversial".
My guess is that the majority of systems out there support hardware  
flow control nowadays.

>
> termios may not be pretty, but it is at least somewhat standardized.
> what else is there as far as serial APIs?  the windows world of
> "everything's a UART" seems incredibly worse.  are there other
> alternatives?

I'm not arguing to get rid of termios, just to cut down on its bloat.

>
> -- 
>   Aaron J. Grier  |   Frye Electronics, Tigard, OR   |  aaron at frye.com
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-- 
Eric Norum <norume at aps.anl.gov>
Advanced Photon Source
Argonne National Laboratory
(630) 252-4793