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Date:      Sun, 25 Feb 2001 02:09:33 -0800 (PST)
From:      John Baldwin <jhb@FreeBSD.org>
To:        Bruce Evans <bde@zeta.org.au>
Cc:        cvs-all@FreeBSD.org, cvs-committers@FreeBSD.org
Subject:   Re: cvs commit: src/sys/i386/conf NOTES src/sys/conf options
Message-ID:  <XFMail.010225020933.jhb@FreeBSD.org>
In-Reply-To: <Pine.BSF.4.21.0102251811400.6130-100000@besplex.bde.org>

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On 25-Feb-01 Bruce Evans wrote:
> On Sat, 24 Feb 2001, John Baldwin wrote:
> 
>> jhb         2001/02/24 11:03:19 PST
>> 
>>   Modified files:
>>     sys/i386/conf        NOTES 
>>     sys/conf             options 
>>   Log:
>>   Add back in INVARIANT_SUPPORT and expand the comments in NOTES about it
>>   to include the reasoning Eivind justifiably thwapped me over the head
>>   with.
> 
> Now removing INVARIANT_SUPPORT is back on my todo list :-].  It enables
> a whole 28 lines of code (the _mtx_assert() function).  It seems to
> be normal for INVARIANTS support code to be this small, so I think it
> should be unconditional.  You got thwapped because _mtx_assert() was
> conditional on the wrong option.  The smallness may have something to
> do with large support code being put under other options, e.g., KTR.

I think Eivind's point was that you may want to just have support for
invariants in your kernel and then build a kernel module that you are debugging
with invariants.  For example, if I wanted to debug a device driver that used
mutexes, I might build it with INVARIANTS so that the mtx_assert()'s do
something useful.  However, I may not wish to turn on INVARIANTS in my base
kernel for some reason, and I can get by by building a kernel with just
INVARIANT_SUPPORT compiled in..

> Bruce

-- 

John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/
PGP Key: http://www.baldwin.cx/~john/pgpkey.asc
"Power Users Use the Power to Serve!"  -  http://www.FreeBSD.org/

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