os-workshop

commit e224e0782865150a3c5f8469a097524b57320022
parent 00dc2d4901bd114fd412e6b491b349a979719379
Author: Brian Swetland <swetland@frotz.net>
Date:   Sat, 14 May 2022 21:17:24 -0700

build: prep for kernel/user projects

- linker script adds __stack_top symbol pointing to top of ram
- start.S now uses that for stack initialization
- new linker scripts for kernel and user type programs

Diffstat:
M
hw/src/start.S
 | 
2
+-
M
make/common.ram.ld
 | 
3
+++
A
make/kernel.ram.ld
 | 
6
++++++
A
make/user.ram.ld
 | 
6
++++++

4 files changed, 16 insertions(+), 1 deletion(-)
diff --git a/hw/src/start.S b/hw/src/start.S
@@ -18,7 +18,7 @@ zero_loop:
 zero_done:
 
 	/* setup initial stack */
-	li sp, (DRAM_BASE + DRAM_SIZE)
+	la sp, __stack_top
 
 	/* enter C code */
 	jal start
diff --git a/make/common.ram.ld b/make/common.ram.ld
@@ -45,4 +45,7 @@ SECTIONS {
 		. = ALIGN(4);
 		__bss_end = .;
 	} > RAM
+
+	/* initialize stack to top of memory */
+	__stack_top = ORIGIN(RAM) + LENGTH(RAM);
 }
diff --git a/make/kernel.ram.ld b/make/kernel.ram.ld
@@ -0,0 +1,6 @@
+
+MEMORY {
+	RAM (rwx) : ORIGIN = 0xC0008000, LENGTH = 0x400000
+}
+
+INCLUDE "make/common.ram.ld"
diff --git a/make/user.ram.ld b/make/user.ram.ld
@@ -0,0 +1,6 @@
+
+MEMORY {
+	RAM (rwx) : ORIGIN = 0x10000000, LENGTH = 0x400000
+}
+
+INCLUDE "make/common.ram.ld"