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Date:      Sun, 10 Nov 2002 13:58:25 -0500
From:      Jake Burkholder <jake@locore.ca>
To:        Matt Jacob <mjacob@FreeBSD.org>
Cc:        cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org
Subject:   Re: cvs commit: src/sys/vm uma_dbg.c
Message-ID:  <20021110135825.B85338@locore.ca>
In-Reply-To: <20021110135614.A85338@locore.ca>; from jake@locore.ca on Sun, Nov 10, 2002 at 01:56:14PM -0500
References:  <200211101616.gAAGGiuV009632@repoman.freebsd.org> <20021110135614.A85338@locore.ca>

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Apparently, On Sun, Nov 10, 2002 at 01:56:14PM -0500,
	Jake Burkholder said words to the effect of;

> Apparently, On Sun, Nov 10, 2002 at 08:16:44AM -0800,
> 	Matt Jacob said words to the effect of;
> 
> > mjacob      2002/11/10 08:16:44 PST
> > 
> >   Modified files:
> >     sys/vm               uma_dbg.c 
> >   Log:
> >   Use atomic_set_8 on the us_freelist maps as they are not otherwise
> >   protected. Furthermore, in some RISC architectures with no normal
> >   byte operations, the surrounding 3 bytes are also affected by the
> >   read-modify-write that has to occur.
> >   
> >   Revision  Changes    Path
> >   1.9       +2 -2      src/sys/vm/uma_dbg.c
> 
> sparc64 can't do atomic operations on less than 32 bits, this needs
> a lock.
> 

fwiw this is in the man page:

     Certain architectures also provide operations for types smaller than
     ``int''.

           char   unsigned character
           short  unsigned short integer
           8      unsigned 8-bit integer
           16     unsigned 16-bit integer

     These must not be used in MI code because the instructions to implement
     them efficiently may not be available.

Jake

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