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    SubjectRe: Regression in ptrace (Wine) starting with 2.6.33-rc1
    On Mon, Feb 15, 2010 at 11:47:24AM -0800, Roland McGrath wrote:
    > > - The other one with 'locally'/'globally' enabled breakpoints.
    >
    > There is no "local/global" enablement. That distinction is meaningless
    > given the way the kernel uses the hardware. Which of those bits you set
    > has no material effect on the watchpoint/trap behavior.



    Yeah.



    > The only regression is in the observed bit pattern read back from dr7.
    > To be 100% compatible, the hw_breakpoint ptrace-compatibility front-end
    > should record the state of the useless bits to report back, so the only
    > differences from the bit pattern written are whatever ones the real
    > hardware would have shown from writing dr7 and reading it back.



    Agreed. We have to match the previous ABI, it's a regression.

    We have the NULL breakpoint address thing fixed (will push it to Ingo).
    We now need to fix the local/global flag storage.

    The fastest way to do so is to keep a per thread dr7 variable.
    I'm looking at it and will send a fix soon.

    We can think about something proper later.

    Thanks.



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