On Wed, 28 Feb 2007, Roland McGrath wrote: > It is true that debug registers are inherited by fork and clone. > I am 99% sure that this was never specifically intended, but it > has been this way for a long time (since 2.4 at least). It's an > implicit consequence of the do_fork implementation style, which > does a blind copy of the whole task_struct and then explicitly > reinitializes some individual fields. I suppose this has some > benefit or other, but it is very prone to new pieces of state > getting implicitly copied without the person adding that new state > ever consciously deciding what its inheritance semantics should be. > > Alan Stern is working on a revamp of the x86 debug register > support. This is a fine opportunity to clean this area up and > decide positively what the semantics ought to be. Absolutely. Right now I just have a placeholder function with a note about checking for CLONE_PTRACE. The cleanest solution, far and away, would be to have the child process inherit no breakpoints and no debug register values. Alan Stern - To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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