lkml.org 
[lkml]   [2005]   [Apr]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: Linux-2.6.11 can't disable CAD
    On Thu, 7 Apr 2005 11:16:14 -0400 (EDT) Richard B. Johnson wrote:

    |
    | In the not-too distant past, one could disable Ctl-Alt-DEL.
    | Can't do it anymore.

    What should disabling C_A_D do?

    | Script started on Thu 07 Apr 2005 10:58:11 AM EDT
    | [SNIPPED leading stuff...]
    |
    | mprotect(0xb7fe4000, 28672, PROT_READ|PROT_EXEC) = 0
    | brk(0) = 0x804a000
    | brk(0x8053000) = 0x8053000
    | reboot(LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2, LINUX_REBOOT_CMD_CAD_OFF) = 0
    | pause( <unfinished ...>
    | _exit(0) = ?
    | # exit
    | Script done on Thu 07 Apr 2005 10:58:21 AM EDT

    What program is that? I'm just echoing 0 | 1 into
    /proc/sys/kernel/ctrl-alt-del , is that equivalent?
    or have you tried that?

    | Observe that reboot() returns 0 and `strace` understands what
    | parameters were passed. The result is that, if I hit Ctl-Alt-Del,
    | `init` will still execute the shutdown-order (INIT 0).

    echo 0 > /proc/sys/kernel/ctrl-alt-del
    is same as CAD_OFF
    echo 1
    is same as CAD_ON

    I tested 2.4.28, 2.6.3, 2.6.9, 2.6.11, and all of them behaved
    the same way for me. If it's an issue with using a syscall
    to change the setting, I'll be glad to look into that too.

    observed behaviors:
    CAD enabled + C_A_D keys => call machine_reboot()
    to reboot quickly, no normal shutdown sequence;
    CAD disabled + C_A_D keys => kill init, go thru normal
    clean shutdown sequence;
    are these the expected behaviors?

    | A side note, while researching this problem, I think I found
    | that LINUX_REBOOT_MAGIC2 is Linus' birthday (in hex). Maybe
    | the problem is that he no longer observes his birthday?

    ---
    ~Randy
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2005-04-07 21:05    [W:0.025 / U:0.992 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site