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From: Roland McGrath <roland@hack.frob.com>
To: Jeff Law <law@redhat.com>
Cc: Maxim Kuvyrkov <maxim@codesourcery.com>,    Andrew Haley <aph@redhat.com>,    David Miller <davem@davemloft.net>,    "Joseph S. Myers" <joseph@codesourcery.com>,    Richard Sandiford <rdsandiford@googlemail.com>,    libc-ports@sourceware.org,    GLIBC Devel <libc-alpha@sourceware.org>,    Chris Metcalf <cmetcalf@tilera.com>
Subject: Re: [PATCH] Unify pthread_spin_[try]lock implementations.
In-Reply-To: Jeff Law's message of  Wednesday, 15 August 2012 11:04:16 -0600 <502BD690.50501@redhat.com>
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> It seems to me that SPIN_LOCK_READS_BETWEEN_CMPXCHG may have the 
> property that varying it at runtime based on the characteristics of the 
> particular chip running the application might be worthwhile.

Nothing prevents a machine from defining the macro to use a global variable
that is set by some machine-specific initialization code.