shutdown doesn't shut down

[Chris Murphy]

On Wed, Feb 4, 2015 at 8:34 AM, Fred Smith
<fredex at fcshome.stoneham.ma.us> wrote:
> On Wed, Feb 04, 2015 at 08:47:46AM -0500, Matthew Miller wrote:
>> On Wed, Feb 04, 2015 at 01:35:13PM +0000, Gary Stainburn wrote:
>> > > doesn't shutdown and halt/power off.
>> > > Instead, these machines shutdown and immediately reboot.
>> > Try
>> > shutdown -h now
>> > The -h means halt
>> > look at
>> [...]
>> > man shutdown
>>
>> Right.... --poweroff should be the default. --halt should bring it to a
>> halted state but leave the power on (not so useful these days), which
>
> I've used "shutdown -h now" ever since I started using LInux (1995), and
> it always shuts down the machine, leaving it powered OFF. My current
> motherboard supports UEFI, but I've disabled it in the BIOS/SETUP
> screens,...  perhaps if I hadn't done that, shutdown -h would work
> differently, but as I said it always has done that.

FYI the motherboard is UEFI, so the "disable UEFI" option actually
means "enable CSM/BIOS" which presents a faux-BIOS to the OS. There is
no actual way to disable UEFI. It's annoying manufacturers use this
vernacular as if words have no meaning.

The only way to know which produces better results is to test it.
Easiest is to use live media and boot twice, once each with this UEFI
setting enabled and disabled. Compare kernel messages for bugs,
problems, or bonuses. For example on one of my computers, CSM/BIOS
boot results in the SSD being treated as an IDE drive, and performs at
best 1/4 of the performance when I boot in UEFI mode. Most of the
video problems in UEFI boot that have been resolved by enabling
CSM/BIOS mode are solved, but... basically you just have to test it to
know for sure.

-- 
Chris Murphy