The following reply was made to PR kern/31572; it has been noted by GNATS.

From: christos@zoulas.com (Christos Zoulas)
To: gnats-bugs@netbsd.org, kern-bug-people@netbsd.org,
	gnats-admin@netbsd.org, netbsd-bugs@netbsd.org
Cc: 
Subject: Re: kern/31572: [dM] tty MIN>1 TIME>0 O_NONBLOCK spins
Date: Thu, 13 Oct 2005 11:30:19 -0400

 On Oct 13,  3:59am, mouse@Rodents.Montreal.QC.CA (der Mouse) wrote:
 -- Subject: kern/31572: [dM] tty MIN>1 TIME>0 O_NONBLOCK spins
 
 | >Number:         31572
 | >Category:       kern
 | >Synopsis:       When MIN>1 TIME>0, poll() on tty succeeds but read EAGAINs
 | >Confidential:   no
 | >Severity:       serious
 | >Priority:       low
 | >Responsible:    kern-bug-people
 | >State:          open
 | >Class:          sw-bug
 | >Submitter-Id:   net
 | >Arrival-Date:   Thu Oct 13 03:59:00 +0000 2005
 | >Originator:     der Mouse
 | >Release:        NetBSD 2.0, also present in 1.4T, probably others
 | >Organization:
 | 	Dis-
 | >Environment:
 | 	First seen on 1.4T sparc.  Tested present on 2.0 i386.  Code
 | 	inspection makes me suspect it's still present in -current.
 | >Description:
 | 	On a tty (tested only on pseudo-ttys, but code inspection makes
 | 	me think it applies to all ttys), when c_cc[VMIN] > 1 and
 | 	c_cc[VTIME] > 0 (and ICANON is off), and non-blocking I/O is
 | 	turned on, then poll() returns indicating readable as soon as
 | 	one character is typed, but a read returns showing EWOULDBLOCK
 | 	until VMIN characters have been received.  (Presumably if
 | 	non-blocking I/O were turned off, read would block instead,
 | 	which is also wrong but not quite as noisily so.)
 | 
 | 	I've marked this as serious/low, serious because it is fairly
 | 	serious for poll and read to disagree like this, but low
 | 	because it obviously doesn't break much or it would have been
 | 	found and fixed long ago.
 | >How-To-Repeat:
 | 	Try the above conditions.  Here's a test program.  Compile it
 | 	(no particular options needed for me on 2.0 i386 or 1.4T sparc)
 | 	and run it with no arguments.  Type a character and watch the
 | 	flood of dots (type a second character to end it; interrupting
 | 	it may leave your tty state hosed).
 
 Isn't that because VTIME expires? linux is behaving the same way.
 
 christos