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    SubjectRe: [PATCH] kdump: Enable kdump if 2nd-kernel is loaded.
    Hi Ohmichi-san,

    Ken'ichi Ohmichi wrote:
    > Hi,
    >
    > This patch enables a kdump if 2nd-kernel is loaded.
    > (The patch is based on linux-2.6.31-rc2.)
    >
    > Now, a kdump is enabled if a kernel parameter "oops=panic" is specified and
    > 2nd-kernel is loaded. I think that a kdump should be enabled regardless of
    > "oops=panic" if 2nd-kernel is loaded, because a system administrator loads
    > 2nd-kernel for enabling a kdump.

    I think this description is slightly wrong because kdump will be invoked
    from panic, regardless of the panic_on_oops.

    Maybe:
    A kdump on oops is enabled if a kernel parameter "oops=panic" ...
    ~~~~~~~

    >
    > * Reference
    > The discussion about this patch
    > http://lists.infradead.org/pipermail/kexec/2009-July/003417.html

    I'd like to quote your comment:

    >> I tried to test a kdump on linux-2.6.31-rc1 *without* a kernel parameter
    >> "oops=panic" by `echo c > /proc/sysrq-trigger`, but a kdump did not work
    >> because a kdump, which is occurred by `echo c > /proc/sysrq-trigger`, has
    >> been changed to a NULL pointer error instead of calling crash_kexec()
    >> since linux-2.6.31-rc1.

    So the real problem is that kdump is not triggered by the NULL pointer oops
    if !panic_on_oops, isn't it?

    It seems that you should report this trouble of sysrq-c as a regression.

    >
    >
    > Thanks
    > Ken'ichi Ohmichi
    >
    > Signed-off-by: Ken'ichi Ohmichi <oomichi@mxs.nes.nec.co.jp>
    > Acked-by: Simon Horman <horms@verge.net.au>
    > ---
    > --- a/kernel/kexec.c 2009-07-08 12:30:26.000000000 +0900
    > +++ b/kernel/kexec.c 2009-07-08 12:38:08.000000000 +0900
    > @@ -57,6 +57,8 @@ struct resource crashk_res = {
    >
    > int kexec_should_crash(struct task_struct *p)
    > {
    > + if (kexec_crash_image)
    > + return 1;
    > if (in_interrupt() || !p->pid || is_global_init(p) || panic_on_oops)
    > return 1;
    > return 0;

    I think kexec cannot crash if there is no image, right?

    Then:

    if (kexec_crash_image)
    return 1;
    return 0;
    or

    return (kexec_crash_image) ? 1 : 0;

    or

    since crash_kexec() is nop if !kexec_crash_image,
    replace all:
    if (kexec_should_crash(p))
    crash_kexec(reg);
    at everywhere in kernel to a simple line:
    crash_kexec(reg);
    and remove kexec_should_crash() completely
    would be better fix.


    Thanks,
    H.Seto



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