Re: Linux-2.6.11 can't disable CAD

[Richard B. Johnson]

It wasn't the kernel.

Many thanks to those who helped me track down this problem.
It seems that the 'C' runtime library was trapping the call
to reboot() which probably should have been _reboot() in
earlier code to prevent this. Anyway, the fix is to call
the kernel directly so it doesn't get blamed for something
it didn't do.

Simple external procedure is attached if anybody else is
interested. It ends up being only 0x30 bytes in length.

Cheers,
Dick Johnson
Penguin : Linux version 2.6.11 on an i686 machine (5537.79 BogoMips).
 Notice : All mail here is now cached for review by Dictator Bush.
                 98.36% of all statistics are fiction.#-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
#
#  Copyright(c)  2005  Analogic Corporation
#
#  This program may be distributed under the GNU Public License
#  version 2, as published by the Free Software Foundation, Inc.,
#  59 Temple Place, Suite 330 Boston, MA, 02111.
#
#-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
#
#   Disable Ctl-Alt-Del
#   Test environment 'C' runtime libraries are screwing with
#   this so I have to call the kernel directly. This is now
#   handled in assembly.
#
#-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

.extern	__set_errno
.LREBOOT = 88
.LMAGIC1 = 0xfee1dead
.LMAGIC2 = 672274793
.LCADOFF = 0x00000000

disable_shutdown:
	pushl	%ebx		# Save precious registers
	pushl	%esi
	movl	$.LREBOOT, %eax	# Reboot command
	movl	$.LMAGIC1, %ebx	# First magic parameter
	movl	$.LMAGIC2, %ecx	# Second magic parameter
	movl	$.LCADOFF, %edx	# Command
	xorl	%esi, %esi	# Zero ignored pointer
	int	$0x80		# Make the call
	popl	%esi		# Restore precious registers
	popl	%ebx
	orl	%eax,%eax	# Check return value
	jns	1f		# It's okay
	negl	%eax		# Make positive
	pushl	%eax
	call	__set_errno	# Set new errno
	addl	$0x04, %esp	# Level stack
	movl	$-1, %eax
1:	ret

.size	disable_shutdown,.-disable_shutdown
.type	disable_shutdown,@function
.global	disable_shutdown
#-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
.end