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From: Peter Wemm <peter@wemm.org>
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Date: Tue, 15 Mar 2005 17:43:49 -0800
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cc: David Schultz <das@freebsd.org>
Subject: Re: Removing kernel thread stack swapping
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On Thursday 03 March 2005 07:35 am, David Schultz wrote:
> On Thu, Mar 03, 2005, John Baldwin wrote:
[..]
> > Hence, don't kill this whole feature just because someone is too
> > lazy to fix a bug.
>
> Fair enough.  I'll defer to you on the extent of the problem.
> David seemed to think that it was more widespread.  (BTW, does
> *anyone* know what the PHOLD() in kern_physio is for?  Is it a
> holdover from when the PCB was in struct user?)

I've wondered about this myself in the past.  I went looking once and 
discovered that it never did anything that I could find.  I believe it 
is a case of 'because it was always done that way' or because the 
pseudocode in the Bach or bsd books had it.  There is certainly no 
functional need for it in FreeBSD.

-- 
Peter Wemm - peter@wemm.org; peter@FreeBSD.org; peter@yahoo-inc.com
"All of this is for nothing if we don't go to the stars" - JMS/B5