os-workshop

commit 076c950cbce75bd1a65f78262f7bfd9832a5724e
parent dc3894952fe274f58ddb0751d171a5dc234104d2
Author: Brian Swetland <swetland@frotz.net>
Date:   Mon,  9 May 2022 11:43:42 -0700

hw: update start code to zero the BSS

Diffstat:
M
hw/src/start.S
 | 
18
++++++++++++++++--

1 file changed, 16 insertions(+), 2 deletions(-)
diff --git a/hw/src/start.S b/hw/src/start.S
@@ -3,11 +3,25 @@
 
 #include <hw/platform.h>
 
+.section ".start"
+
 .globl _start
 _start:
+	/* zero BSS */
+	la t0, __bss_start
+	la t1, __bss_end
+zero_loop:
+	beq t0, t1, zero_done
+	sw zero, 0(t0)
+	add a0, a0, 4
+	j zero_loop
+zero_done:
+
+	/* setup initial stack */
 	li sp, (DRAM_BASE + DRAM_SIZE)
+
+	/* enter C code */
 	jal start
 
-.globl exit
-exit:
+	/* infinite loop */
 	j .