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Date: Tue, 23 Oct 2012 18:42:11 +0400
From: Gleb Smirnoff <glebius@FreeBSD.org>
To: Andre Oppermann <andre@FreeBSD.org>
Subject: Re: svn commit: r241931 - in head/sys: conf kern
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References: <201210231419.q9NEJjYH082863@svn.freebsd.org>
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On Tue, Oct 23, 2012 at 02:19:45PM +0000, Andre Oppermann wrote:
A> Author: andre
A> Date: Tue Oct 23 14:19:44 2012
A> New Revision: 241931
A> URL: http://svn.freebsd.org/changeset/base/241931
A> 
A> Log:
A>   Replace the ill-named ZERO_COPY_SOCKET kernel option with two
A>   more appropriate named kernel options for the very distinct
A>   send and receive path.
A>   
A>   "options SOCKET_SEND_COW" enables VM page copy-on-write based
A>   sending of data on an outbound socket.
A>   
A>   NB: The COW based send mechanism is not safe and may result
A>   in kernel crashes.
A>   
A>   "options SOCKET_RECV_PFLIP" enables VM kernel/userspace page
A>   flipping for special disposable pages attached as external
A>   storage to mbufs.
A>   
A>   Only the naming of the kernel options is changed and their
A>   corresponding #ifdef sections are adjusted.  No functionality
A>   is added or removed.
A>   
A>   Discussed with:	alc (mechanism and limitations of send side COW)

Users may call this a pointless POLA violation. IMO, the old
kernel option that we had for years, more than a decade, should remain
and just imply two new kernel options.


-- 
Totus tuus, Glebius.