Add special linker script stanza for CAN message RAM

Author: jepler

variants/feather_m4_can/linker_scripts/gcc/flash_with_bootloader.ld

@@ -143,6 +143,15 @@ SECTIONS
 
 	__etext = .;
 
+	/* Data accessed by the CAN peripheral must be in the first 64kB RAM */
+	/* place it at the very start of RAM, before the .data section */
+	/* *NOTE* it is not expliclty zeroed */
+	.canram (NOLOAD) :
+	{
+	    . = ALIGN(4);
+	    *(.canram)
+	} > RAM
+
 	.data : AT (__etext)
 	{
 		__data_start__ = .;

variants/feather_m4_can/linker_scripts/gcc/flash_without_bootloader.ld

@@ -141,6 +141,15 @@ SECTIONS
 
 	__etext = .;
 
+	/* Data accessed by the CAN peripheral must be in the first 64kB RAM */
+	/* place it at the very start of RAM, before the .data section */
+	/* *NOTE* it is not expliclty zeroed */
+	.canram (NOLOAD) :
+	{
+	    . = ALIGN(4);
+	    *(.canram)
+	} > RAM
+
 	.data : AT (__etext)
 	{
 		__data_start__ = .;