Kernel pty limit

Kevin Kinsey kdk at
Thu Nov 15 12:43:15 PST 2007

Christopher Cowart wrote:
> Hello,
> I went to open up a new shell to our login server (recently rebuilt from
> Debian to FreeBSD) and found problems allocating a new pty. With a
> 256-pty limit, I'm surprised more people haven't had this problem. With
> team of 8 SysAdmins, each leaving about 30 windows open in screen
> sessions, 256 starts feeling a bit claustrophobic. 

Hmm, 8 guys root on one boxen?  Sounds like a "cushy" job!
Got an IP and a couple of partners I could play xtank with?

J/k, of course.   :-D
> I found a questions thread from January 2006 and these PRs:
> standards/90896: not enough PTYs in the FreeBSD
> kern/25866: [patch] more than 256 ptys, up to 1302 ptys.

There was also discussion on hackers@ at the time[1], and a
mention from rwatson@ that a new tty_pts.c and support in libc
for this was added to HEAD then[2]; I haven't checked, but I'm
assuming it's still in the new 7 branch and will be a part
of 7.0 Real Soon Now(tm), if that's any comfort.  There may
be patches available, there was some discussion.  Also, if it
*IS* in 7.0, I guess you could holler for a MFC.

> The latter appears to have been kicking around since FreeBSD 4.3 (still
> open). 
> What can I do to help get that limit raised? Does anyone have a patch
> against 6.2? If not, would anyone be interested in writing one?
> Thanks for any help,


Kevin Kinsey

Break into jail and claim police brutality.


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