Simple New Feature Request: Compile default slackware kernel with CONFIG_MAGIC_SYSRQ enabled - Slackware

This is a discussion on Simple New Feature Request: Compile default slackware kernel with CONFIG_MAGIC_SYSRQ enabled - Slackware ; Hi, sometimes when your system is extremely frozen, then you can recover it to atleast reboot safely by pressing in many situations by pressing Alt+SysRq and some key combination (which is esp. useful in case your PC is not on ...

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Thread: Simple New Feature Request: Compile default slackware kernel with CONFIG_MAGIC_SYSRQ enabled

  1. Simple New Feature Request: Compile default slackware kernel with CONFIG_MAGIC_SYSRQ enabled

    Hi,
    sometimes when your system is extremely frozen, then you can recover
    it to atleast reboot safely by pressing in many situations by pressing
    Alt+SysRq and some key combination (which is esp. useful in case your
    PC is not on network, on your PC has hanged so badly that even ssh is
    not responding)
    kindly refer to
    http://en.wikipedia.org/wiki/Magic_SysRq_key
    http://www.wains.be/index.php/2007/0...frozen-system/

    I have seen that ubuntu kernel is compiled with this option, but
    slackware is not. It would have been a great service, if default
    supplied slackware kernel would have been compiled with this switch.
    as some of my machines hang after 15-20 days of uptime, in that case
    it will be useful feature.

    bye :-)
    Ashish


  2. Re: Simple New Feature Request: Compile default slackware kernelwith CONFIG_MAGIC_SYSRQ enabled

    ashishwave a écrit :
    >
    > I have seen that ubuntu kernel is compiled with this option, but
    > slackware is not. It would have been a great service, if default
    > supplied slackware kernel would have been compiled with this switch.
    > as some of my machines hang after 15-20 days of uptime, in that case
    > it will be useful feature.


    As we say in my native Austria:

    Es gibt nichts Gutes,
    Ausser man tut es.

    Meaning roughly: There's no good thing unless you do it.

    If you have several machines, well, take the pain to rebuild your kernel
    with that option, and then repackage it. AFAIK, that's what Slackware is
    about. )

    Cheers,

    Niki Kovacs

  3. Re: Simple New Feature Request: Compile default slackware kernelwith CONFIG_MAGIC_SYSRQ enabled

    Wed, 26 Sep 2007 11:20:32 +0000, ashishwave did catÂ*:

    > Hi,
    > sometimes when your system is extremely frozen, then you can recover
    > it to atleast reboot safely by pressing in many situations by pressing
    > Alt+SysRq and some key combination (which is esp. useful in case your PC
    > is not on network, on your PC has hanged so badly that even ssh is not
    > responding)
    > kindly refer to
    > http://en.wikipedia.org/wiki/Magic_SysRq_key
    > http://www.wains.be/index.php/2007/0...frozen-system/
    >
    > I have seen that ubuntu kernel is compiled with this option, but
    > slackware is not. It would have been a great service, if default
    > supplied slackware kernel would have been compiled with this switch.


    Not that sure on my side, I personally use kernels compiled with
    this option but that's mainly because I compile my own kernels for
    many different reasons (mostly related to audio, RTC and crypts)
    but that's also the reason why I ever have had to use the MagicKeys :-)

    > as some of my machines hang after 15-20 days of uptime, in that case
    > it will be useful feature.


    I'd say you can take the time to rebuild the native kernel with
    just the addup of the SysReq (CONFIG_MAGIC_SYSRQ=y), that'd be easy
    as you won't try and use different libs and headers.

    Though I'd say you'll get some time and pain saved if you
    concentrate on the very reasons that made some of your machines
    freeze after 15-20 days uptime, which never was an innocent symptom )

  4. Re: Simple New Feature Request: Compile default slackware kernel with CONFIG_MAGIC_SYSRQ enabled

    On 2007-09-26, ashishwave wrote:
    > Hi,
    > sometimes when your system is extremely frozen, then you can recover
    > it to atleast reboot safely by pressing in many situations by pressing
    > Alt+SysRq and some key combination (which is esp. useful in case your
    > PC is not on network, on your PC has hanged so badly that even ssh is
    > not responding)
    > kindly refer to
    > http://en.wikipedia.org/wiki/Magic_SysRq_key
    > http://www.wains.be/index.php/2007/0...frozen-system/
    >
    > I have seen that ubuntu kernel is compiled with this option, but
    > slackware is not. It would have been a great service, if default
    > supplied slackware kernel would have been compiled with this switch.
    > as some of my machines hang after 15-20 days of uptime, in that case
    > it will be useful feature.



    You haven't read this, have you?
    http://slackware.osuosl.org/slackware-12.0/UPGRADE.TXT

    The Slackware kernels now include support for the "magic SysRQ key."
    For more information about what this is and how it can be used, see
    /usr/src/linux-2.6.21.5/Documentation/sysrq.txt
    After you've read this, if you would like to disable it, there are at
    least two ways to do so.
    1. Add the following to /etc/sysctl.conf (note that this file does not
    exist by default, so you'll have to create it):
    kernel.sysrq = 0
    2. Add the following to one of the init scripts (preferably rc.local):
    echo 0 > /proc/sys/kernel/sysrq
    The first method has the advantage of being run from rc.S when the system
    first comes up, while the second will be run only after the system is in
    multi-user mode. It's up to you as to which is better.

    RW

  5. Re: Simple New Feature Request: Compile default slackware kernel with CONFIG_MAGIC_SYSRQ enabled

    ashishwave wrote:

    > It would have been a great service, if default supplied slackware kernel
    > would have been compiled with this switch.


    It has been pointed out by others before that this newsgroup is very rarely
    if ever read by the proprietor of Slackware®, and that suggestions or
    requests for inclusion of some specific software are best addressed to him
    via http://www.slackware.com/contact/
    --
    Two Ravens
    "...hit the squirrel..."

  6. Re: Simple New Feature Request: Compile default slackware kernel with CONFIG_MAGIC_SYSRQ enabled

    ashishwave wrote:

    > I have seen that ubuntu kernel is compiled with this option, but
    > slackware is not. It would have been a great service, if default
    > supplied slackware kernel would have been compiled with this switch.
    > as some of my machines hang after 15-20 days of uptime, in that case
    > it will be useful feature.


    Well, RW posted the real answer. However, I believe it wasn't included
    in the past because it involved turning on kernel hacking, and there were,
    according to the documentation the last time I read it, potential performance
    impacts. Also, some commands, such as the SAK (Secure Access Key) would
    break the majority of Linux distros. Really, all those options were
    nice, but probably not considered mature to be included in a stable
    production environment. Slackware has never been about adding such options
    by default. Ubuntu and Slackware have two very different design philosophies.

    If your computers are hanging after 15-20 days, something is wrong with
    your setup, or hardware. If the computers are on a network, give a shot
    at telnet'ing into them from another computer, to kill things off.
    The magic keys 's' 'u' and 'r' options are more of a last resort
    before pulling the power options (kind of like "Stop A" on a Sun box).

    - Kurt


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