As of grub-2:2.06.r297.g0c6c1aff2-1-aarch64 as packaged by Arch Linux ARM (which is vanilla grub as of that git revision, other than grub.d patches and trivial packaging-related changes), initializing graphics fails on Apple M1 Pro MacBook 14" systems, and probably others, with an out of memory error. This leads to a degraded text console with broken menu graphic characters. This didn't happen with the previous package (grub-2.06.r261.g2f4430cc0-1).

The open source boot stack on these systems uses U-Boot as an EFI services provider. It seems GRUB is simply running out of heap as of recent changes. This trivial patch fixes it:

diff -urN grub-core/kern/efi/mm.c grub-core/kern/efi/mm.c
--- grub-core/kern/efi/mm.c     2022-08-20 20:17:23.975902981 +0900
+++ grub-core/kern/efi/mm.c     2022-08-20 20:17:16.268139945 +0900
@@ -39,7 +39,7 @@
 #define MEMORY_MAP_SIZE        0x3000

 /* The default heap size for GRUB itself in bytes.  */
-#define DEFAULT_HEAP_SIZE      0x100000
+#define DEFAULT_HEAP_SIZE      0x200000

 static void *finish_mmap_buf = 0;
 static grub_efi_uintn_t finish_mmap_size = 0;