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    SubjectRe: Why dump_stack results different so much?
    Thanks for your reply.

    Below is the code that print the kernel calling trace:

    void show_trace(struct task_struct *task, unsigned long * stack)
    unsigned long ebp;

    if (!task)
    task = current;

    if (task == current) {
    /* Grab ebp right from our regs */
    asm ("movl %%ebp, %0" : "=r" (ebp) : );
    } else {
    /* ebp is the last reg pushed by switch_to */
    ebp = *(unsigned long *) task->thread.esp;

    while (1) {
    struct thread_info *context;
    context = (struct thread_info *)
    ((unsigned long)stack & (~(THREAD_SIZE - 1)));
    ebp = print_context_stack(context, stack, ebp);
    stack = (unsigned long*)context->previous_esp;
    if (!stack)
    printk(" =======================\n");

    From this code, I can see that the show_trace does not scan and guess
    the pointers. Instead, it use "previous_esp" to extract the esp and
    thus the returning eip. Am I right?


    On 7/29/05, bert hubert <> wrote:
    > On Fri, Jul 29, 2005 at 04:27:16PM -0400, Xin Zhao wrote:
    > > I supprisely noticed that the dump_stack results are quite different!
    > > Why did I get the calling traces below our_ssy_open() and above
    > > syscall_call()? Any thought on this? Many thanks!
    > This might depend on compiling with frame pointers, or not. I recall that at
    > one point, the kernel did a basic scan of addresses that looked like likely
    > candidates to have been pointers, and printed those.
    > Frame pointers are hailed as improving backtraces. They are in the 'kernel
    > hacking' section of the kernel configuration.
    > Sorry that I can't be more precise, but try turning on frame pointers.
    > Good luck!
    > --
    > Open source, database driven DNS Software
    > Open and Closed source services
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