git: 052a791b0055 - main - acpi: add Darwin OSI quirk for Apple Mac hardware

The branch main has been updated by adrian:

URL: https://cgit.FreeBSD.org/src/commit/?id=052a791b00555805f19ccc38a04d42d48b54104b

commit 052a791b00555805f19ccc38a04d42d48b54104b
Author:     Abdelkader Boudih <freebsd@seuros.com>
AuthorDate: 2026-02-03 01:43:00 +0000
Commit:     Adrian Chadd <adrian@FreeBSD.org>
CommitDate: 2026-02-03 01:51:37 +0000

    acpi: add Darwin OSI quirk for Apple Mac hardware
    
    Mac firmware hides the Intel integrated GPU (iGPU) on dual GPU x86
    systems, i.e., with AMD/NVIDIA dGPUs, when the Darwin OSI is not
    installed via ACPI.
    
    Prior to this change, FreeBSD always used the dGPU. This is fine in
    practice, but consumed more power than when the iGPU is used,
    resulting in reduced battery life.
    
    Linux handles this in `drivers/acpi/osi.c` by detecting Apple
    hardware via DMI, disabling all Windows OSI strings, and
    by explicitly installing the Darwin OSI ACPI handler. This change
    applies equivalent logic to the acpi(4) driver on FreeBSD.
    
    This feature can be enabled/disabled using the
    `hw.acpi.apple_darwin_osi` tunable. Setting this tunable to `0`
    restores the previous behavior by explicitly disabling the added
    support.
    
    Reviewed by:    obiwac, ngie, adrian
    Differential Revision:  https://reviews.freebsd.org/D54762
---
 sys/dev/acpica/acpi.c | 72 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 72 insertions(+)

diff --git a/sys/dev/acpica/acpi.c b/sys/dev/acpica/acpi.c
index 60a2dba91b05..8cdb73333462 100644
--- a/sys/dev/acpica/acpi.c
+++ b/sys/dev/acpica/acpi.c
@@ -293,6 +293,17 @@ static char acpi_remove_interface[256];
 TUNABLE_STR("hw.acpi.remove_interface", acpi_remove_interface,
     sizeof(acpi_remove_interface));
 
+/*
+ * Automatically apply the Darwin OSI on Apple Mac hardware to obtain
+ * access to full ACPI hardware support on supported platforms.
+ *
+ * This flag automatically overrides any values set by
+ * `hw.acpi.acpi_install_interface` and unset by
+ * `hw.acpi.acpi_remove_interface`.
+ */
+static int acpi_apple_darwin_osi = 1;
+TUNABLE_INT("hw.acpi.apple_darwin_osi", &acpi_apple_darwin_osi);
+
 /* Allow users to dump Debug objects without ACPI debugger. */
 static int acpi_debug_objects;
 TUNABLE_INT("debug.acpi.enable_debug_objects", &acpi_debug_objects);
@@ -4903,6 +4914,67 @@ acpi_reset_interfaces(device_t dev)
 		}
 		acpi_free_interfaces(&list);
 	}
+
+	/*
+	 * Apple Mac hardware quirk: install Darwin OSI.
+	 *
+	 * On Apple hardware, install the Darwin OSI and remove the Windows OSI
+	 * to match Linux behavior.
+	 *
+	 * This is required for dual-GPU MacBook Pro systems
+	 * (Intel iGPU + AMD/NVIDIA dGPU) where the iGPU is hidden when the
+	 * firmware doesn't see Darwin OSI, but it also unlocks additional ACPI
+	 * support on non-MacBook Pro Apple platforms.
+	 *
+	 * Apple's ACPI firmware checks _OSI("Darwin") and sets OSYS=10000
+	 * for macOS. Many device methods use OSDW() which checks OSYS==10000
+	 * for macOS-specific behavior including GPU visibility and power
+	 * management.
+	 *
+	 * Linux enables Darwin OSI by default on Apple hardware and disables
+	 * all Windows OSI strings (drivers/acpi/osi.c). Users can override
+	 * this behavior with acpi_osi=!Darwin to get Windows-like behavior,
+	 * in general, but this logic makes that process unnecessary.
+	 *
+	 * Detect Apple via SMBIOS and enable Darwin while disabling Windows
+	 * vendor strings. This makes both GPUs visible on dual-GPU MacBook Pro
+	 * systems (Intel iGPU + AMD dGPU) and unlocks full platform
+	 * ACPI support.
+	 */
+	if (acpi_apple_darwin_osi) {
+		char *vendor = kern_getenv("smbios.system.maker");
+		if (vendor != NULL) {
+			if (strcmp(vendor, "Apple Inc.") == 0 ||
+			    strcmp(vendor, "Apple Computer, Inc.") == 0) {
+				/* Disable all other OSI vendor strings. */
+				status = AcpiUpdateInterfaces(
+				    ACPI_DISABLE_ALL_VENDOR_STRINGS);
+				/* Install Darwin */
+				if (ACPI_SUCCESS(status)) {
+					status = AcpiInstallInterface("Darwin");
+				}
+				if (bootverbose) {
+					if (ACPI_SUCCESS(status)) {
+						device_printf(dev,
+						    "Apple hardware: installed Darwin "
+						    "OSI and removed other vendor OSI "
+						    "(Windows, etc)\n");
+					} else {
+						device_printf(dev,
+						    "Apple hardware: failed to install "
+						    "Darwin OSI: %s\n",
+						    AcpiFormatException(
+							status));
+					}
+				}
+			} else if (bootverbose) {
+				device_printf(dev,
+				    "Not installing Darwin OSI on unsupported platform: %s\n",
+				    vendor);
+			}
+			freeenv(vendor);
+		}
+	}
 }
 
 static int