lkml.org 
[lkml]   [2011]   [Jul]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    Date
    SubjectRE: [RFC][PATCH -mmotm 0/4] Improvement of pstore/kmsg_dump in kexec/panic path
    Hi Vivek,

    > Why can't we log something in user space when user initiates a reboot,
    > Why does kernel need to capture that info in NVRAM.

    As I explained in following thread,
    customers sometimes ask us to investigate the reason why system reboots.

    https://lkml.org/lkml/2010/11/17/249

    We can solve following scenario by logging messages in kernel space.

    - Syslogd is killed by mistake.
    (user kills syslogd with command or other applications send signal).
    - And then, system reboots.

    If we log messages in user space, we can't see messages.

    Seiji

    >-----Original Message-----
    >From: Vivek Goyal [mailto:vgoyal@redhat.com]
    >Sent: Tuesday, July 19, 2011 2:48 PM
    >To: Seiji Aguchi
    >Cc: kexec@lists.infradead.org; linux-kernel@vger.kernel.org; linux-mtd@lists.infradead.org; Eric W. Biederman; KOSAKI
    >Motohiro; Americo Wang; Matthew Garrett; tony.luck@intel.com; Andrew Morton; Jarod Wilson; hpa@zytor.com;
    >dzickus@redhat.com; dle-develop@lists.sourceforge.net; Satoru Moriya
    >Subject: Re: [RFC][PATCH -mmotm 0/4] Improvement of pstore/kmsg_dump in kexec/panic path
    >
    >On Tue, Jul 19, 2011 at 02:23:26PM -0400, Seiji Aguchi wrote:
    >> Hi,
    >>
    >> [Upstream status]
    >> Discussion about kmsg_dump() in kdump path:
    >> - Eric and Vivek are worried about reliability of existing kmsg_dump().
    >> - Especially, Vivek would like to remove a RCU function call chain in kdump path
    >>     which kernel modules can register their function calls freely.
    >>
    >> Discussion about pstore in nmi_hander.
    >> - Don Zickus found an issue of pstore in nmi_handler due to its mutex_lock.
    >
    >You did not answer my questions in the last posting mail thread and gone
    >ahead with the new posting. How are we supposed to discuss something. This
    >has been a problem on this mail thread since the beginneing. There is
    >little open discussion.
    >
    >So if you want to make any progress in this direction, what will help
    >is open discussion.
    >
    >Locking is going to be a problem. So atleast we can remove kmsg_dump()
    >infrastructure from reboot path. Why can't we log something in user
    >space when user initiates a reboot, let it get logged in /var/log/messages
    >and then umount the file root and go ahead with reboot. Why does kernel
    >need to capture that info in NVRAM.
    >
    >If we can get rid of all the logging thing on reboot path, then at least
    >it does not need to be lock protected with crash path.
    >
    >Thanks
    >Vivek
    \
     
     \ /
      Last update: 2011-07-21 00:37    [W:0.025 / U:62.516 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site