On Thu, 7 Apr 2005 15:46:20 -0400 (EDT) Richard B. Johnson wrote: | On Thu, 7 Apr 2005, Randy.Dunlap wrote: | | > 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 | > | | It's a program that executes the __NR_reboot syscall (88) after | putting the documented values into the appropriate registers.
Yeah, I understood that much. Just wondering if it was available somewhere... | > 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? | > | | Doesn't matter. Many embedded systems don't have /proc because | they don't have any file-systems. It matters if they are equivalent (and I don't have that program above). | > | 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? | | The expected behavior of the reported operation is for | Ctl-Alt-Del to no longer do anything. If the system-call | has been depreciated, then the call should return -1 and | errno should be ENOSYS. In such a case, I would have | to trap the key-sequence in some other way, not that | I know how without modifying the kernel. Have you looked at 'man 2 reboot'? It seems to agree with the observed behavior (above). or where should I look to find documentation of the expected behavior that you described? --- ~Randy - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
