ACPI is enabled by default. dmesg output:

BIOS-provided physical RAM map:
BIOS-e820: 0000000000000000 - 000000000009fc00 (usable)
BIOS-e820: 000000000009fc00 - 00000000000a0000 (reserved)
BIOS-e820: 00000000000e0000 - 0000000000100000 (reserved)
BIOS-e820: 0000000000100000 - 000000003fcf7000 (usable)
BIOS-e820: 000000003fcf7000 - 000000003fcff000 (reserved)
BIOS-e820: 000000003fcff000 - 000000003fdbd000 (usable)
BIOS-e820: 000000003fdbd000 - 000000003fdbf000 (reserved)
BIOS-e820: 000000003fdbf000 - 000000003fe8a000 (usable)
BIOS-e820: 000000003fe8a000 - 000000003febf000 (ACPI NVS)
BIOS-e820: 000000003febf000 - 000000003ff00000 (ACPI data)
BIOS-e820: 000000003ff00000 - 0000000040000000 (reserved)
BIOS-e820: 00000000e0000000 - 00000000f0000000 (reserved)
.......
DMI 2.3 present.
ACPI: RSDP 000FE020, 0014 (r0 NEC )
ACPI: RSDT 3FEFE038, 0034 (r1 NEC H2O 1 1000013)
ACPI: FACP 3FEFD000, 0074 (r1 NEC H2O 1 MSFT 1000013)
ACPI: DSDT 3FEF8000, 4CDB (r1 NEC H2O 1 MSFT 1000013)
ACPI: FACS 3FE8A000, 0040
ACPI: SSDT 3FEF7000, 020A (r1 NEC H2O 1 MSFT 1000013)
ACPI: APIC 3FEF6000, 0068 (r1 NEC H2O 1 MSFT 1000013)
ACPI: MCFG 3FEF4000, 003C (r1 NEC H2O 1 MSFT 1000013)
ACPI: PM-Timer IO Port: 0x408
ACPI: Local APIC address 0xfee00000
ACPI: LAPIC (acpi_id[0x01] lapic_id[0x00] enabled)
.....
Enabling APIC mode: Flat. Using 1 I/O APICs
Using ACPI (MADT) for SMP configuration information
....

Regards