Subj : Re: Consistency of a byte shared variable
To   : comp.programming.threads
From : David Schwartz
Date : Mon Jan 31 2005 10:46 pm


"theepan" <theepan@wavenet.lk> wrote in message
news:1107236114.818222.64200@c13g2000cwb.googlegroups.com...

    The answers are:

> C,

    The C standard says nothing about this.

> POSIX,

    POSIX requires locks around all accesses to shared variables. See the 
POSIX memory visibility rules.

> linux

    Linux follows POSIX.

> x86

    x86 will definitely have word tearing issues, theoretically. However all 
currently existing x86 processors, I believe, have a clever trick that 
causes this not to actually be a problem (a speculative fetch is pegged to 
its cache line and invalidated if the cache line is lost). Experts seem to 
even be unsure.

    DS

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