coreboot

Supermicro X9SCM-iiF, debian sid (4.19.0-1-amd64) or stable (4.9.0-8-amd64):

% git clone https://review.coreboot.org/coreboot.git
% cd coreboot/util/intelmetool
% make
% s ./intelmetool -m
Bad news, you have a `C204 Chipset LPC Controller` so you have ME hardware on board and you can't control or disable it, continuing...

MEI found: [8086:1c3a] 6 Series/C200 Series Chipset Family MEI Controller #1

ME Status   : 0x21f0382
ME Status 2 : 0x101db000

ME: FW Partition Table      : OK
ME: Bringup Loader Failure  : NO
ME: Firmware Init Complete  : YES
ME: Manufacturing Mode      : NO
ME: Boot Options Present    : NO
ME: Update In Progress      : NO
ME: Current Working State   : Recovery
ME: Current Operation State : Bring up
ME: Current Operation Mode  : (null)
ME: Error Code              : No Error
ME: Progress Phase          : BUP Phase
ME: Power Management Event  : Clean Moff->Mx wake
ME: Progress Phase State    : 0x1d

ME: Extend Register not valid

Error mapping physical memory 0x0000000804265984 [0x2000] ERRNO=1 Operation not permitted
Could not map ME setup memory.
Do you have kernel cmdline argument 'iomem=relaxed' set ?

Yes, I've set 'iomem=relaxed':

% cat /proc/cmdline 
BOOT_IMAGE=/boot/vmlinuz-4.9.0-8-amd64 root=UUID=<UUID> ro consoleblank=0 console=tty1 console=ttyS2,115200n8 forcefsck iomem=relaxed