2 files changed, 20 insertions, 5 deletions
diff --git a/tmk_core/common/arm_atsam/eeprom.c b/tmk_core/common/arm_atsam/eeprom.c
index 5c8e69dae3..ccd5d15a54 100644
--- a/tmk_core/common/arm_atsam/eeprom.c
+++ b/tmk_core/common/arm_atsam/eeprom.c
@@ -16,9 +16,12 @@
 
 #include "eeprom.h"
 
-#define EEPROM_SIZE 32
+#ifndef EEPROM_SIZE
+#    include "eeconfig.h"
+#    define EEPROM_SIZE (((EECONFIG_SIZE + 3) / 4) * 4)  // based off eeconfig's current usage, aligned to 4-byte sizes, to deal with LTO
+#endif
 
-static uint8_t buffer[EEPROM_SIZE];
+__attribute__((aligned(4))) static uint8_t buffer[EEPROM_SIZE];
 
 uint8_t eeprom_read_byte(const uint8_t *addr) {
     uintptr_t offset = (uintptr_t)addr;
diff --git a/tmk_core/common/chibios/eeprom_teensy.c b/tmk_core/common/chibios/eeprom_teensy.c
index 45f9a530da..d436d0cb95 100644
--- a/tmk_core/common/chibios/eeprom_teensy.c
+++ b/tmk_core/common/chibios/eeprom_teensy.c
@@ -50,7 +50,16 @@
 // (aligned to 2 or 4 byte boundaries) has twice the endurance
 // compared to writing 8 bit bytes.
 //
-#    define EEPROM_SIZE 32
+#    ifndef EEPROM_SIZE
+#        define EEPROM_SIZE 32
+#    endif
+
+/*
+    ^^^ Here be dragons:
+        NXP AppNote AN4282 section 3.1 states that partitioning must only be done once.
+        Once EEPROM partitioning is done, the size is locked to this initial configuration.
+        Attempts to modify the EEPROM_SIZE setting may brick your board.
+*/
 
 // Writing unaligned 16 or 32 bit data is handled automatically when
 // this is defined, but at a cost of extra code size.  Without this,
@@ -517,8 +526,11 @@ void eeprom_write_block(const void *buf, void *addr, uint32_t len) {
 #else
 // No EEPROM supported, so emulate it
 
-#    define EEPROM_SIZE 64
-static uint8_t buffer[EEPROM_SIZE];
+#    ifndef EEPROM_SIZE
+#        include "eeconfig.h"
+#        define EEPROM_SIZE (((EECONFIG_SIZE + 3) / 4) * 4)  // based off eeconfig's current usage, aligned to 4-byte sizes, to deal with LTO
+#    endif
+__attribute__((aligned(4))) static uint8_t buffer[EEPROM_SIZE];
 
 uint8_t eeprom_read_byte(const uint8_t *addr) {
     uint32_t offset = (uint32_t)addr;