[PATCH linux-next] x86_32: fix VisualWS and Voyager kexec build failures

[Randy Dunlap <randy.dunlap@oracle.com>]

From: Randy Dunlap <randy.dunlap@oracle.com>

cc: Eric Biederman <ebiederm@xmission.com>

Both Visual WS and Voyager builds fail in almost the same way (in
linux-next) without this patch:

VOYAGER:
kernel/built-in.o: In function `crash_kexec':
(.text+0x28588): undefined reference to `machine_crash_shutdown'

VISWS:
kernel/built-in.o: In function `crash_kexec':
/next-20080401/kernel/kexec.c:1074: undefined reference to `machine_crash_shutdown'
make[1]: *** [.tmp_vmlinux1] Error 1

because arch/x86/kernel/reboot.c isn't built since CONFIG_X86_BIOS_REBOOT=n,
so machine_crash_shutdown() isn't available.

This patch does seem a small bit odd since the KEXEC help text says that
kexec is independent of the system firmware.

Eric, is there some other way that this should be handled?

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
---
 arch/x86/Kconfig |    1 +
 1 file changed, 1 insertion(+)

--- next-20080401.orig/arch/x86/Kconfig
+++ next-20080401/arch/x86/Kconfig
@@ -1094,6 +1094,7 @@ source kernel/Kconfig.hz
 
 config KEXEC
 	bool "kexec system call"
+	depends on X86_64 || X86_BIOS_REBOOT
 	help
 	  kexec is a system call that implements the ability to shutdown your
 	  current kernel, and to start another kernel.  It is like a reboot