Integrate Hall and riscv target

wuehans/start.S

@@ -0,0 +1,54 @@
+.section .text.startSection
+.global _Z4mainv
+.global _start
+
+_start:
+/* zero-initialize all registers */
+addi x1, zero, 0
+addi x2, zero, 0
+addi x3, zero, 0
+addi x4, zero, 0
+addi x5, zero, 0
+addi x6, zero, 0
+addi x7, zero, 0
+addi x8, zero, 0
+addi x9, zero, 0
+addi x10, zero, 0
+addi x11, zero, 0
+addi x12, zero, 0
+addi x13, zero, 0
+addi x14, zero, 0
+addi x15, zero, 0
+addi x16, zero, 0
+addi x17, zero, 0
+addi x18, zero, 0
+addi x19, zero, 0
+addi x20, zero, 0
+addi x21, zero, 0
+addi x22, zero, 0
+addi x23, zero, 0
+addi x24, zero, 0
+addi x25, zero, 0
+addi x26, zero, 0
+addi x27, zero, 0
+addi x28, zero, 0
+addi x29, zero, 0
+addi x30, zero, 0
+addi x31, zero, 0
+
+/* set stack pointer */
+.equ STACK_START, 0x02000000
+lui sp, %hi(STACK_START)
+addi sp, sp, %lo(STACK_START)
+
+/* push zeros on the stack for argc and argv */
+/* (stack is aligned to 16 bytes in riscv calling convention) */
+addi sp,sp,-16
+sw zero,0(sp)
+sw zero,4(sp)
+sw zero,8(sp)
+sw zero,12(sp)
+
+/* jump to libc init */
+// j _Z4mainv
+j main