== baseline ==
hw.gmuxobs_scr: 0
== kldload apple_gmux (production module) ==
ACPI: SSDT 0x00000000BFFE1CAC 00005A (v00 AUDIT  GMUXRIG1 00000001 INTL 00000001)
gmuxobs: COM1 SCR (0x3ff) at module load = 0x00
apple_gmux0: <apple gmux controller> port 0x333-0x336 on acpi0
apple_gmux: gmux device not present or IO disabled
device_probe_and_attach: apple_gmux0 attach returned -19
== canary after ==
hw.gmuxobs_scr: 170