From 24b46a5fff2f25a6ce362d6003093baef03290d0 Mon Sep 17 00:00:00 2001
From: Sebastian <sebastian@sebastians-site.de>
Date: Sun, 28 Dec 2025 13:07:42 +0100
Subject: [PATCH] Fixed memory layout to avoid running into segfaults

---
 firmware/src/bootloader.rs | 18 ++++++------------
 memory.x                   | 16 +---------------
 2 files changed, 7 insertions(+), 27 deletions(-)

diff --git a/firmware/src/bootloader.rs b/firmware/src/bootloader.rs
index 0c87fe3..c186b18 100644
--- a/firmware/src/bootloader.rs
+++ b/firmware/src/bootloader.rs
@@ -1,5 +1,5 @@
 use core::mem::MaybeUninit;
-use core::ptr::addr_of_mut;
+
 use stm32f4xx_hal::pac;
 
 fn jump_to_bootloader() {
@@ -23,25 +23,19 @@ fn jump_to_bootloader() {
 
 const BOOTLOADER_REQUESTED: u32 = 0xdecafbad;
 
-fn magic_mut_ptr() -> *mut u32 {
-    extern "C" {
-        #[link_name = "_dfu_magic"]
-        static mut magic: u32;
-    }
-
-    unsafe { addr_of_mut!(magic) }
-}
+#[link_section = ".uninit.DFU_FLAG"]
+static mut DFU_FLAG: MaybeUninit<u32> = MaybeUninit::uninit();
 
 fn get_bootloader_flag() -> u32 {
-    unsafe { magic_mut_ptr().read_volatile() }
+    unsafe { DFU_FLAG.assume_init() }
 }
 
 fn set_bootloader_flag() {
-    unsafe { magic_mut_ptr().write_volatile(BOOTLOADER_REQUESTED) };
+    unsafe { DFU_FLAG.write(BOOTLOADER_REQUESTED) };
 }
 
 fn clear_bootloader_flag() {
-    unsafe { magic_mut_ptr().write_volatile(BOOTLOADER_REQUESTED) };
+    unsafe { DFU_FLAG.write(0) };
 }
 
 pub fn init() {
diff --git a/memory.x b/memory.x
index 33fd2a3..78b279a 100644
--- a/memory.x
+++ b/memory.x
@@ -1,23 +1,9 @@
 MEMORY
 {
   FLASH : ORIGIN = 0x08000000, LENGTH = 256K 
-  UNINIT : ORIGIN = 0x20000000, LENGTH = 0x10
-  RAM : ORIGIN = 0x20000010, LENGTH = 64K - LENGTH(UNINIT)
+  RAM : ORIGIN = 0x20000000, LENGTH = 64K
 }
 
-SECTIONS {
-  .uninit_flags (NOLOAD) : ALIGN(4)
-  {
-    . = ALIGN(4);
-    __suninit_flags = .;
-    _dfu_magic = .; . += 4;
-    *(.uninit_flags .uninit_flags.*)
-    . = ALIGN(4);
-    __euninit_flags = .;
-  } > UNINIT
-}
-
-
 /* This is where the call stack will be allocated. */
 /* The stack is of the full descending type. */
 /* NOTE Do NOT modify `_stack_start` unless you know what you are doing */