RE: termios VMIN and VTIME behavior

[Alan Cox]

On Maw, 2005-11-22 at 20:32 -0800, Mike Voytovich wrote:
> Please disregard - the user app was reading less than VMIN in the read()
> call, so I suppose the current behavior in that case would be correct
> (returning immediately with the number of bytes passed into read()
> rather than waiting for VMIN or VTIME to be met before returning).
> 
> It doesn't appear that the behavior in this case is explicitly defined
> by POSIX, but it seems like a reasonable thing to do.

Its pretty well defined. It was designed to optimise block serial
operations (uucp and the like)

	VMIN	-	number of bytes you expect this packet
	VTIME   -	when to give up waiting

The form 0, VTIME also being used to do polling on old SYSV that lacked
select/poll

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