systemd-boot patch to set max UEFI resolution

systemd.diff

diff --git a/src/boot/efi/boot.c b/src/boot/efi/boot.c
index 1e990b382..c7471aaac 100644
--- a/src/boot/efi/boot.c
+++ b/src/boot/efi/boot.c
@@ -492,6 +492,7 @@ static BOOLEAN menu_run(Config *config, ConfigEntry **chosen_entry, CHAR16 *load
         BOOLEAN wait = FALSE;
 
         graphics_mode(FALSE);
+        set_max_resolution();
         uefi_call_wrapper(ST->ConIn->Reset, 2, ST->ConIn, FALSE);
         uefi_call_wrapper(ST->ConOut->EnableCursor, 2, ST->ConOut, FALSE);
         uefi_call_wrapper(ST->ConOut->SetAttribute, 2, ST->ConOut, EFI_LIGHTGRAY|EFI_BACKGROUND_BLACK);
diff --git a/src/boot/efi/graphics.c b/src/boot/efi/graphics.c
index 4854baf87..c6540a2af 100644
--- a/src/boot/efi/graphics.c
+++ b/src/boot/efi/graphics.c
@@ -86,3 +86,38 @@ EFI_STATUS graphics_mode(BOOLEAN on) {
 
         return err;
 }
+
+EFI_STATUS set_max_resolution() {
+    EFI_GUID GraphicsOutputProtocolGuid = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
+    EFI_GRAPHICS_OUTPUT_PROTOCOL *GraphicsOutput = NULL;
+    EFI_STATUS err;
+
+    UINTN i;
+    UINTN width, height;
+    UINTN best_mode = 0, best_width = 0, best_height = 0;
+    UINTN graphics_info_size;
+    EFI_GRAPHICS_OUTPUT_MODE_INFORMATION *graphics_info;
+
+    err = LibLocateProtocol(&GraphicsOutputProtocolGuid, (VOID **)&GraphicsOutput);
+    if (EFI_ERROR(err))
+        return err;
+
+    for (i = 0; i < GraphicsOutput->Mode->MaxMode; i++) {
+        err = uefi_call_wrapper(GraphicsOutput->QueryMode, 4, GraphicsOutput, i, &graphics_info_size, &graphics_info);
+        if (err == EFI_SUCCESS) {
+            width = graphics_info->HorizontalResolution;
+            height = graphics_info->VerticalResolution;
+            if (width > best_width || (width == best_width && height > best_height)) {
+                best_mode = i;
+                best_width = width;
+                best_height = height;
+            }
+        }
+    }
+
+    if (best_mode != GraphicsOutput->Mode->Mode) {
+        return uefi_call_wrapper(GraphicsOutput->SetMode, 2, GraphicsOutput, best_mode);
+    }
+
+    return EFI_SUCCESS;
+}
diff --git a/src/boot/efi/graphics.h b/src/boot/efi/graphics.h
index cf48e647e..ba9c4c6eb 100644
--- a/src/boot/efi/graphics.h
+++ b/src/boot/efi/graphics.h
@@ -19,4 +19,6 @@
 #define __SDBOOT_GRAPHICS_H
 
 EFI_STATUS graphics_mode(BOOLEAN on);
+
+EFI_STATUS set_max_resolution();
 #endif