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Date: Thu, 12 Apr 2012 04:04:25 +0100
From: Al Viro <viro@ZenIV.linux.org.uk>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Kay Sievers <kay@vrfy.org>, "Ted Ts'o" <tytso@mit.edu>,
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        Greg Kroah-Hartman <gregkh@linux-foundation.org>,
        Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Subject: Re: RFC: deprecating/removing the legacy mode of devpts
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On Wed, Apr 11, 2012 at 07:48:44PM -0700, H. Peter Anvin wrote:
> The symlink support is at least 3 years old, probably more.

DEVPTS_MULTIPLE_INSTANCES wasn't anywhere near mandatory all that time...
Kernel upgrade procedure that starts with "build the old kernel with
that option enabled, boot it, replace /dev/ptmx with a symlink, then
never try to boot earlier kernel images.  Now you can safely upgrade
to current kernel" is the recipe for massive self-LARTs (and resulting
pitchfork crowds).