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    From
    SubjectRe: year old problem
    Date
    Followup to:  <19991116004726.A3036@fred.muc.de>
    By author: Andi Kleen <ak@muc.de>
    In newsgroup: linux.dev.kernel
    >
    > On Mon, Nov 15, 1999 at 11:36:31PM +0100, Eric Pouech wrote:
    > > well, it seems to me that the code in __switch_to (loaddebug macro) *restores*
    > > the DBi registers (from the tss in memory to the i386) while switching to 'next'
    > > process
    > >
    > > my issue is that the i386 value of DR6 (status => which debug registers
    > > which (may) have triggered a trap) are never (I should say no longer)
    > > stored in tss as they used to be (and therefore never accessible with ptrace)
    > >
    > > in 2.0.x series, they were stored in tss while entering the TRAP handler
    > > and it's no longer the case.
    >
    > Point taken. It seems to be a bug.
    > For DR0-DR3/DR7 it doesn't make sense to save them all the time (because they
    > can be set by ptrace, even by the program), but DR4-6 should be saved.
    >

    There is no DR4 and DR5.

    -=hpa
    --
    <hpa@transmeta.com> at work, <hpa@zytor.com> in private!
    "Unix gives you enough rope to shoot yourself in the foot."

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