From a5f0f4eb3bd10d0eb0667b394921658c2f22b06d Mon Sep 17 00:00:00 2001
From: Matthew Kennedy <makenne@microsoft.com>
Date: Fri, 27 Nov 2020 19:58:38 -0800
Subject: [PATCH] custom linker script

---
 firmware/Makefile           |  6 +--
 firmware/cfg/STM32F042x6.ld | 86 +++++++++++++++++++++++++++++++++++++
 2 files changed, 89 insertions(+), 3 deletions(-)
 create mode 100644 firmware/cfg/STM32F042x6.ld

diff --git a/firmware/Makefile b/firmware/Makefile
index 527ffac..6b0cef3 100644
--- a/firmware/Makefile
+++ b/firmware/Makefile
@@ -5,7 +5,7 @@
 
 # Compiler options here.
 ifeq ($(USE_OPT),)
-  USE_OPT = -O2 -ggdb -fomit-frame-pointer -falign-functions=16
+  USE_OPT = -O2 -ggdb -fomit-frame-pointer -falign-functions=16 -fsingle-precision-constant
 endif
 
 # C specific options here (added to USE_OPT).
@@ -15,7 +15,7 @@ endif
 
 # C++ specific options here (added to USE_OPT).
 ifeq ($(USE_CPPOPT),)
-  USE_CPPOPT = -fno-rtti -fno-exceptions -ffast-math -funsafe-math-optimizations
+  USE_CPPOPT = -fno-rtti -fno-exceptions -ffast-math -funsafe-math-optimizations -fno-threadsafe-statics -fno-use-cxa-atexit
 endif
 
 # Enable this if you want the linker to remove unused code and data.
@@ -111,7 +111,7 @@ include $(CHIBIOS)/tools/mk/autobuild.mk
 include $(CHIBIOS)/os/hal/lib/streams/streams.mk
 
 # Define linker script file here
-LDSCRIPT= $(STARTUPLD)/STM32F042x6.ld
+LDSCRIPT= $(CONFDIR)/STM32F042x6.ld
 
 # C sources that can be compiled in ARM or THUMB mode depending on the global
 # setting.
diff --git a/firmware/cfg/STM32F042x6.ld b/firmware/cfg/STM32F042x6.ld
new file mode 100644
index 0000000..b49d750
--- /dev/null
+++ b/firmware/cfg/STM32F042x6.ld
@@ -0,0 +1,86 @@
+/*
+    ChibiOS - Copyright (C) 2006..2018 Giovanni Di Sirio
+
+    Licensed under the Apache License, Version 2.0 (the "License");
+    you may not use this file except in compliance with the License.
+    You may obtain a copy of the License at
+
+        http://www.apache.org/licenses/LICENSE-2.0
+
+    Unless required by applicable law or agreed to in writing, software
+    distributed under the License is distributed on an "AS IS" BASIS,
+    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+    See the License for the specific language governing permissions and
+    limitations under the License.
+*/
+
+/*
+ * STM32F042x6 memory setup.
+ */
+MEMORY
+{
+    /* bootloader (rx) : org = 0x08000000, len = 8k */
+    flash0 (rx) : org = 0x08000000, len = 24k
+    flash1 (rx) : org = 0x00000000, len = 0
+    flash2 (rx) : org = 0x00000000, len = 0
+    flash3 (rx) : org = 0x00000000, len = 0
+    flash4 (rx) : org = 0x00000000, len = 0
+    flash5 (rx) : org = 0x00000000, len = 0
+    flash6 (rx) : org = 0x00000000, len = 0
+    flash7 (rx) : org = 0x00000000, len = 0
+    ram0   (wx) : org = 0x20000000, len = 6k
+    ram1   (wx) : org = 0x00000000, len = 0
+    ram2   (wx) : org = 0x00000000, len = 0
+    ram3   (wx) : org = 0x00000000, len = 0
+    ram4   (wx) : org = 0x00000000, len = 0
+    ram5   (wx) : org = 0x00000000, len = 0
+    ram6   (wx) : org = 0x00000000, len = 0
+    ram7   (wx) : org = 0x00000000, len = 0
+}
+
+/* For each data/text section two region are defined, a virtual region
+   and a load region (_LMA suffix).*/
+
+/* Flash region to be used for exception vectors.*/
+REGION_ALIAS("VECTORS_FLASH", flash0);
+REGION_ALIAS("VECTORS_FLASH_LMA", flash0);
+
+/* Flash region to be used for constructors and destructors.*/
+REGION_ALIAS("XTORS_FLASH", flash0);
+REGION_ALIAS("XTORS_FLASH_LMA", flash0);
+
+/* Flash region to be used for code text.*/
+REGION_ALIAS("TEXT_FLASH", flash0);
+REGION_ALIAS("TEXT_FLASH_LMA", flash0);
+
+/* Flash region to be used for read only data.*/
+REGION_ALIAS("RODATA_FLASH", flash0);
+REGION_ALIAS("RODATA_FLASH_LMA", flash0);
+
+/* Flash region to be used for various.*/
+REGION_ALIAS("VARIOUS_FLASH", flash0);
+REGION_ALIAS("VARIOUS_FLASH_LMA", flash0);
+
+/* Flash region to be used for RAM(n) initialization data.*/
+REGION_ALIAS("RAM_INIT_FLASH_LMA", flash0);
+
+/* RAM region to be used for Main stack. This stack accommodates the processing
+   of all exceptions and interrupts.*/
+REGION_ALIAS("MAIN_STACK_RAM", ram0);
+
+/* RAM region to be used for the process stack. This is the stack used by
+   the main() function.*/
+REGION_ALIAS("PROCESS_STACK_RAM", ram0);
+
+/* RAM region to be used for data segment.*/
+REGION_ALIAS("DATA_RAM", ram0);
+REGION_ALIAS("DATA_RAM_LMA", flash0);
+
+/* RAM region to be used for BSS segment.*/
+REGION_ALIAS("BSS_RAM", ram0);
+
+/* RAM region to be used for the default heap.*/
+REGION_ALIAS("HEAP_RAM", ram0);
+
+/* Generic rules inclusion.*/
+INCLUDE rules.ld