..
So next is inside the kernel itself, at linux/kernel/sys.c :: sys_reboot(),
where we see this code:
/* Instead of trying to make the power_off code look like
* halt when pm_power_off is not set do it the easy way.
*/
if ((cmd == LINUX_REBOOT_CMD_POWER_OFF) && !pm_power_off)
cmd = LINUX_REBOOT_CMD_HALT;
This converts a "poweroff" into a "reboot" if no machine dependent
power off function has been bound in (pm_power_off() is a function pointer).
So for this to work, I believe that either ACPI or APM has to have been-
configured into the kernel (and the modules loaded). Your kernel .config
from earlier shows ACPI built-in to the kernel core, so it should be present.
Unless you booted with noacpi or some such parameter..
So let's have a look at the kernel boot logs,
and you could also try CONGIG_ACPI_DEBUG=y
Bizarre (and nothing to do with my patch).