stratomancer · March 2, 2026 11:04 · Mar 2, 2026 · Mar 2, 2026
diff --git a/MacBookPro-force-Intel-GPU.md b/MacBookPro-force-Intel-GPU.md
@@ -1,6 +1,6 @@
 # Linux Mint on MacBookPro 11,5: force Intel iGPU + power off Radeon dGPU (repro guide)
 
-This is a reproducible setup for **Linux Mint (UEFI)** on a **2015 MacBook Pro 11,5** (Intel Haswell iGPU + AMD Radeon dGPU + Apple GMUX). It is based on the work of Bruno Bierbaumer https://github.com/0xbb/apple_set_os.efi and credits belong to Andreas Heider who originally discovered this hack:
+This is a guide for improving the power consumption on Linux Mint 22.2 by disabling the Radeon GPU and enabling the Intel GPU on a **2015 MacBook Pro 11,5** (Intel Haswell iGPU + AMD Radeon dGPU + Apple GMUX). It is based on the work of Bruno Bierbaumer https://github.com/0xbb/apple_set_os.efi and credits belong to Andreas Heider who originally discovered this hack:
 https://lists.gnu.org/archive/html/grub-devel/2013-12/msg00442.html
 
 I simply adapted it to work on Linux Mint 22.2.

diff --git a/MacBookPro-force-Intel-GPU.md b/MacBookPro-force-Intel-GPU.md
@@ -0,0 +1,393 @@
+# Linux Mint on MacBookPro 11,5: force Intel iGPU + power off Radeon dGPU (repro guide)
+
+This is a reproducible setup for **Linux Mint (UEFI)** on a **2015 MacBook Pro 11,5** (Intel Haswell iGPU + AMD Radeon dGPU + Apple GMUX). It is based on the work of Bruno Bierbaumer https://github.com/0xbb/apple_set_os.efi and credits belong to Andreas Heider who originally discovered this hack:
+https://lists.gnu.org/archive/html/grub-devel/2013-12/msg00442.html
+
+I simply adapted it to work on Linux Mint 22.2.
+
+Goal:
+- Boot in a way that **exposes/keeps the Intel iGPU usable** (some Mac firmware disables or hides it for non-macOS boots).
+- Ensure the **internal panel (eDP) is driven by i915**.
+- **Power off the Radeon dGPU** so it stops draining the battery.
+
+The configuration uses:
+1) **rEFInd** as the first-stage boot manager.
+2) A small UEFI app that calls Apple’s private `apple_set_os` protocol (spoofs macOS vendor/version) **and then chainloads GRUB/shim**.
+3) A **systemd oneshot service** that runs on every boot to switch to Intel and power off the dGPU via `vga_switcheroo`.
+
+---
+
+## 0) Assumptions / notes
+
+- You are booting in **UEFI mode**.
+- Your EFI System Partition (ESP) is mounted at **`/boot/efi`**.
+- You have **sudo** privileges.
+- Secure Boot: this guide chainloads `shimx64.efi` first, so it works with Secure Boot setups too (assuming shim is properly installed).
+
+---
+
+## 1) Install required packages
+
+```bash
+sudo apt update
+sudo apt install -y git make gcc gnu-efi efibootmgr pciutils tlp
+```
+
+(You may already have some of these.)
+
+---
+
+## 2) Confirm your GPUs and that GMUX exists
+
+```bash
+lspci -nnk | awk 'BEGIN{IGNORECASE=1} /(vga|3d|display)/{p=1} p{print} /^$/{p=0}'
+
+dmesg | egrep -i 'apple_gmux|gmux|i915|radeon|amdgpu' | tail -n 200
+```
+
+You should see something like:
+- Intel iGPU: `00:02.0` (i915)
+- AMD dGPU: `01:00.0` (radeon)
+- `apple_gmux: Found gmux ...`
+
+---
+
+## 3) Build the EFI wrapper: `apple_set_os_grub_chain.efi`
+
+### 3.1 Get the apple_set_os source
+
+```bash
+mkdir -p /tmp/apple-set-os-chain
+cd /tmp/apple-set-os-chain
+rm -rf apple-set-os
+git clone --depth 1 https://github.com/kekrby/apple-set-os.git
+cd apple-set-os
+```
+
+### 3.2 Add the chainloading variant source
+
+Create a new file `apple_set_os_grub_chain.c`:
+
+```bash
+cat > apple_set_os_grub_chain.c <<'EOF'
+// apple_set_os_grub_chain
+// 1) Call Apple's apple_set_os protocol to set OS vendor/version
+// 2) Chainload GRUB/shim from the same ESP/device
+
+#include <efibind.h>
+#include <efidef.h>
+#include <efidevp.h>
+#include <eficon.h>
+#include <efiprot.h>
+#include <efiapi.h>
+#include <efierr.h>
+
+#define APPLE_SET_OS_VENDOR  "Apple Inc."
+#define APPLE_SET_OS_VERSION "Mac OS X 10.9"
+
+static EFI_GUID APPLE_SET_OS_GUID = { 0xc5c5da95, 0x7d5c, 0x45e6, { 0xb2, 0xf1, 0x3f, 0xd5, 0x2b, 0xb1, 0x00, 0x77 } };
+static EFI_GUID EFI_LOADED_IMAGE_GUID = EFI_LOADED_IMAGE_PROTOCOL_GUID;
+static EFI_GUID EFI_DEVICE_PATH_GUID  = EFI_DEVICE_PATH_PROTOCOL_GUID;
+
+typedef struct _APPLE_SET_OS_INTERFACE {
+    UINT64 Version;
+    EFI_STATUS (EFIAPI *SetOsVersion) (IN CHAR8 *Version);
+    EFI_STATUS (EFIAPI *SetOsVendor) (IN CHAR8 *Vendor);
+} APPLE_SET_OS_INTERFACE;
+
+static UINTN str_len16(const CHAR16 *s) {
+    UINTN n = 0;
+    while (s && s[n]) n++;
+    return n;
+}
+
+static void mem_copy(void *dst, const void *src, UINTN n) {
+    UINT8 *d = (UINT8 *)dst;
+    const UINT8 *s = (const UINT8 *)src;
+    while (n--) *d++ = *s++;
+}
+
+static void say(SIMPLE_TEXT_OUTPUT_INTERFACE *ConOut, const CHAR16 *msg) {
+    if (ConOut && msg) ConOut->OutputString(ConOut, (CHAR16 *)msg);
+}
+
+static UINTN device_path_size(EFI_DEVICE_PATH_PROTOCOL *dp) {
+    UINTN sz = 0;
+    if (!dp) return 0;
+    while (!IsDevicePathEnd(dp)) {
+        sz += DevicePathNodeLength(dp);
+        dp = NextDevicePathNode(dp);
+    }
+    sz += END_DEVICE_PATH_LENGTH;
+    return sz;
+}
+
+static EFI_DEVICE_PATH_PROTOCOL *build_full_device_path(EFI_BOOT_SERVICES *BS,
+                                                        EFI_DEVICE_PATH_PROTOCOL *device_dp,
+                                                        const CHAR16 *file_path) {
+    // Build full device path: [device_dp without END] + FILEPATH node + END
+
+    UINTN dev_sz = device_path_size(device_dp);
+    if (dev_sz < END_DEVICE_PATH_LENGTH) return NULL;
+
+    UINTN file_path_bytes = (str_len16(file_path) + 1) * sizeof(CHAR16);
+    UINTN file_node_sz = sizeof(FILEPATH_DEVICE_PATH) + file_path_bytes - sizeof(CHAR16);
+
+    UINTN total = (dev_sz - END_DEVICE_PATH_LENGTH) + file_node_sz + END_DEVICE_PATH_LENGTH;
+
+    EFI_DEVICE_PATH_PROTOCOL *out = NULL;
+    if (EFI_ERROR(BS->AllocatePool(EfiLoaderData, total, (VOID **)&out)) || !out)
+        return NULL;
+
+    mem_copy(out, device_dp, dev_sz - END_DEVICE_PATH_LENGTH);
+
+    FILEPATH_DEVICE_PATH *fp = (FILEPATH_DEVICE_PATH *)((UINT8 *)out + (dev_sz - END_DEVICE_PATH_LENGTH));
+    fp->Header.Type = MEDIA_DEVICE_PATH;
+    fp->Header.SubType = MEDIA_FILEPATH_DP;
+    SetDevicePathNodeLength(&fp->Header, file_node_sz);
+    mem_copy(fp->PathName, file_path, file_path_bytes);
+
+    EFI_DEVICE_PATH_PROTOCOL *end = (EFI_DEVICE_PATH_PROTOCOL *)((UINT8 *)fp + file_node_sz);
+    SetDevicePathEndNode(end);
+
+    return out;
+}
+
+static EFI_STATUS try_chainload(EFI_HANDLE Image, EFI_SYSTEM_TABLE *SystemTable, const CHAR16 *path) {
+    EFI_STATUS Status;
+
+    EFI_LOADED_IMAGE *LoadedImage = NULL;
+    Status = SystemTable->BootServices->HandleProtocol(Image, &EFI_LOADED_IMAGE_GUID, (VOID **) &LoadedImage);
+    if (EFI_ERROR(Status) || LoadedImage == NULL)
+        return Status;
+
+    EFI_DEVICE_PATH_PROTOCOL *DeviceDp = NULL;
+    Status = SystemTable->BootServices->HandleProtocol(LoadedImage->DeviceHandle, &EFI_DEVICE_PATH_GUID, (VOID **) &DeviceDp);
+    if (EFI_ERROR(Status) || DeviceDp == NULL)
+        return Status;
+
+    EFI_DEVICE_PATH_PROTOCOL *FullDp = build_full_device_path(SystemTable->BootServices, DeviceDp, path);
+    if (FullDp == NULL)
+        return EFI_OUT_OF_RESOURCES;
+
+    EFI_HANDLE ChildImage = NULL;
+    Status = SystemTable->BootServices->LoadImage(FALSE, Image, FullDp, NULL, 0, &ChildImage);
+    SystemTable->BootServices->FreePool(FullDp);
+
+    if (EFI_ERROR(Status))
+        return Status;
+
+    say(SystemTable->ConOut, L"Starting: ");
+    say(SystemTable->ConOut, path);
+    say(SystemTable->ConOut, L"\r\n");
+
+    Status = SystemTable->BootServices->StartImage(ChildImage, NULL, NULL);
+    return Status;
+}
+
+EFI_STATUS
+efi_main(EFI_HANDLE Image, EFI_SYSTEM_TABLE *SystemTable)
+{
+    EFI_STATUS Status;
+    APPLE_SET_OS_INTERFACE *SetOs = NULL;
+
+    say(SystemTable->ConOut, L"apple_set_os_grub_chain started\r\n");
+
+    // Apple protocol: set vendor/version to "Mac OS X" values
+    Status = SystemTable->BootServices->LocateProtocol(&APPLE_SET_OS_GUID, NULL, (VOID **) &SetOs);
+    if (!EFI_ERROR(Status) && SetOs != NULL) {
+        if (SetOs->Version != 0)
+            SetOs->SetOsVersion((CHAR8 *) APPLE_SET_OS_VERSION);
+        SetOs->SetOsVendor((CHAR8 *) APPLE_SET_OS_VENDOR);
+    }
+
+    // Try common distro paths on ESP
+    const CHAR16 *targets[] = {
+        L"\\EFI\\ubuntu\\shimx64.efi",
+        L"\\EFI\\ubuntu\\grubx64.efi",
+        L"\\EFI\\linuxmint\\shimx64.efi",
+        L"\\EFI\\linuxmint\\grubx64.efi",
+        L"\\EFI\\debian\\grubx64.efi",
+        L"\\EFI\\BOOT\\BOOTX64.EFI",
+        NULL
+    };
+
+    for (int i = 0; targets[i] != NULL; i++) {
+        Status = try_chainload(Image, SystemTable, targets[i]);
+        if (!EFI_ERROR(Status))
+            return Status;
+    }
+
+    say(SystemTable->ConOut, L"No GRUB target could be chainloaded.\r\n");
+    return EFI_NOT_FOUND;
+}
+EOF
+```
+
+### 3.3 Update the Makefile to build both EFI binaries
+
+```bash
+perl -0777 -i -pe 's/^TARGET\t=\s*apple_set_os\.efi\s*$/TARGETS\t= apple_set_os.efi apple_set_os_grub_chain.efi\n\n# Backward compatible single-target alias\nTARGET\t= apple_set_os.efi/m;
+               s/^all:\s*\$\(TARGET\)\s*$/all: \$\(TARGETS\)/m;
+               s/^clean:\n\t.*$/clean:\n\trm -f \$\(TARGETS\) *.so *.o/m;' Makefile
+```
+
+### 3.4 Build
+
+```bash
+make clean
+make -j"$(nproc)"
+ls -la *.efi
+```
+
+You should have:
+- `apple_set_os.efi`
+- `apple_set_os_grub_chain.efi`
+
+---
+
+## 4) Install the wrapper into the ESP
+
+This guide installs it to: **`/boot/efi/EFI/tools/apple_set_os_grub_chain.efi`**
+
+```bash
+sudo mkdir -p /boot/efi/EFI/tools
+sudo cp -f apple_set_os_grub_chain.efi /boot/efi/EFI/tools/apple_set_os_grub_chain.efi
+sudo chmod 0644 /boot/efi/EFI/tools/apple_set_os_grub_chain.efi
+```
+
+Confirm your GRUB/shim path exists (Mint often uses `EFI/ubuntu` if installed in Ubuntu-compatible mode):
+
+```bash
+sudo find /boot/efi/EFI -maxdepth 3 -type f -iname '*.efi' | sed -n '1,200p'
+```
+
+---
+
+## 5) Configure rEFInd to boot through the wrapper
+
+### 5.1 Install rEFInd (if not already installed)
+
+Mint package (simple):
+
+```bash
+sudo apt install -y refind
+sudo refind-install
+```
+
+### 5.2 Add a rEFInd menu entry
+
+Edit:
+- `/boot/efi/EFI/refind/refind.conf`
+
+Append:
+
+```conf
+# Chainload: set Apple OS vendor/version then boot GRUB
+menuentry "Apple Set OS -> GRUB" {
+    icon /EFI/refind/icons/os_linux.png
+    loader /EFI/tools/apple_set_os_grub_chain.efi
+}
+```
+
+Reboot and select **Apple Set OS -> GRUB**.
+
+---
+
+## 6) Power off the Radeon dGPU after boot (persistent)
+
+Create a systemd service:
+
+```bash
+sudo tee /etc/systemd/system/apple-set-os-dgpu-off.service >/dev/null <<'UNIT'
+[Unit]
+Description=Power off Radeon dGPU on dual-GPU Mac after boot (vga_switcheroo)
+After=multi-user.target
+
+[Service]
+Type=oneshot
+ExecStart=/bin/sh -c 'mountpoint -q /sys/kernel/debug || mount -t debugfs none /sys/kernel/debug'
+ExecStart=/bin/sh -c 'test -e /sys/kernel/debug/vgaswitcheroo/switch && echo IGD > /sys/kernel/debug/vgaswitcheroo/switch || true'
+ExecStart=/bin/sh -c 'test -e /sys/kernel/debug/vgaswitcheroo/switch && echo OFF > /sys/kernel/debug/vgaswitcheroo/switch || true'
+RemainAfterExit=yes
+
+[Install]
+WantedBy=multi-user.target
+UNIT
+
+sudo systemctl daemon-reload
+sudo systemctl enable --now apple-set-os-dgpu-off.service
+```
+
+---
+
+## 7) Verification checklist
+
+### 7.1 Verify internal panel is on Intel
+
+```bash
+for s in /sys/class/drm/card*-eDP-*/status; do
+  [ -r "$s" ] && echo "$(basename "$(dirname "$s")") : $(cat "$s")"
+done | sort
+
+dmesg | egrep -i 'fbcon:.*primary device|i915' | tail -n 50
+```
+
+Expected:
+- Intel `card?-eDP-?` shows `connected`
+- `fbcon: i915drmfb (fb0) is primary device`
+
+### 7.2 Verify dGPU is off
+
+```bash
+sudo cat /sys/kernel/debug/vgaswitcheroo/switch
+```
+
+Expected:
+- `DIS` shows `Off`
+- `IGD` shows `+` and `Pwr`
+
+### 7.3 Use TLP to verify state
+
+```bash
+sudo tlp-stat -s
+sudo tlp-stat -g
+```
+
+TLP will show the `vgaswitcheroo` status.
+
+---
+
+## 8) Rollback / recovery
+
+### Remove the dGPU-off service
+
+```bash
+sudo systemctl disable --now apple-set-os-dgpu-off.service
+sudo rm -f /etc/systemd/system/apple-set-os-dgpu-off.service
+sudo systemctl daemon-reload
+```
+
+### Remove the wrapper
+
+```bash
+sudo rm -f /boot/efi/EFI/tools/apple_set_os_grub_chain.efi
+```
+
+### Remove the rEFInd menu entry
+
+Edit `/boot/efi/EFI/refind/refind.conf` and delete the `menuentry "Apple Set OS -> GRUB" { ... }` stanza.
+
+### If you can’t boot
+
+Use the Mac’s firmware boot picker (Option key) to boot your normal “Ubuntu” shim entry, or boot rEFInd and pick the default Mint/Ubuntu loader directly.
+
+---
+
+## 9) Notes / tuning
+
+- On this hardware, `vgaswitcheroo` shows `DIS: Off` even if PCI runtime PM still reads `active`. The important indicator is **the switcheroo state** and the fact that Intel eDP is connected.
+- For additional idle power tuning, use:
+  - `sudo tlp-stat -w` (warnings)
+  - `sudo tlp-stat -e` (PCIe runtime PM)
+  - `sudo tlp-stat -d` (SATA ALPM)
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