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    SubjectRe: 2.5.4 Compile Error
    On Mon, 2002-02-11 at 01:02, John Weber wrote:

    > The function thread_saved_pc() is a mystery to me. It is declared with
    > a return type of unsigned long, and yet return this:
    > ((unsigned long *)tsk->thread->esp)[3]
    > This is confusing to me in many ways:
    > - the "thread" member of task struct is not a pointer
    > - esp is of type unsigned long, so I don't understand the cast, and
    > I certainly don't understand the [3] here.
    > Can anyone explain this code to me?

    The problem is an interdependency between processor.h and sched.h.

    The old code was the same, except it did


    where t was a thread_struct, instead of what we do now


    where t is a task_struct. And thus whereby before we passed


    as the argument, now you pass just `p'. I.e., its the same net-affect.
    The error is because the function needs access to both task_struct (in
    sched.h) and thread_struct (in processor.h) but the two are interrelated
    so we can't include them in each other.

    The contents of esp is a memory address, so typecasting it to (unsigned
    long *) is OK.

    As for the [3], p[3] is the same as
    so that is legal.

    So the fix, aside from reverting this change and the kernel/sched.c
    change and the sparc64 changes ... would be to solve the dependency

    Robert Love

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