feat(user): add user-space build system and init process to test fork/wait

3 files changed, 92 insertions, 0 deletions

diff --git a/src/user/init.cc b/src/user/init.cc
new file mode 100644
index 0000000..3c42adf
--- /dev/null
+++ b/src/user/init.cc
@@ -0,0 +1,34 @@
+#include "user/user.h"
+
+int main();
+
+extern "C" void _start()
+{
+    exit(main());
+}
+
+int main()
+{
+    int pid = fork();
+
+    if (pid < 0)
+    {
+        write(1, "Fork failed\n", 12);
+        exit(1);
+    }
+
+    if (pid == 0)
+    {
+        write(1, "Hello from Child!\n", 18);
+        exit(0);
+    }
+    else
+    {
+        write(1, "Parent waiting...\n", 18);
+        wait(0);
+        write(1, "Parent: Child exited.\n", 22);
+    }
+
+    while (1);
+    return 0;
+}
\ No newline at end of file
diff --git a/src/user/user.ld b/src/user/user.ld
new file mode 100644
index 0000000..2111b14
--- /dev/null
+++ b/src/user/user.ld
@@ -0,0 +1,27 @@
+OUTPUT_ARCH(riscv)
+ENTRY(_start)
+
+SECTIONS
+{
+  . = 0x0;
+  
+  .text : {
+    *(.text.entry)
+    *(.text .text.*)
+  }
+
+  .rodata : {
+    . = ALIGN(16);
+    *(.rodata .rodata.*)
+  }
+
+  .data : {
+    . = ALIGN(16);
+    *(.data .data.*)
+  }
+
+  .bss : {
+    . = ALIGN(16);
+    *(.bss .bss.*)
+  }
+}
\ No newline at end of file
diff --git a/src/user/usys.S b/src/user/usys.S
new file mode 100644
index 0000000..e805d82
--- /dev/null
+++ b/src/user/usys.S
@@ -0,0 +1,31 @@
+#include "kernel/syscall.h"
+
+#define SYSCALL(name) \
+    .global name; \
+    name: \
+        li a7, SYS_ ## name; \
+        ecall; \
+        ret
+
+SYSCALL(fork)
+SYSCALL(exit)
+SYSCALL(wait)
+SYSCALL(pipe)
+SYSCALL(read)
+SYSCALL(write)
+SYSCALL(close)
+SYSCALL(kill)
+SYSCALL(exec)
+SYSCALL(open)
+SYSCALL(mknod)
+SYSCALL(unlink)
+SYSCALL(fstat)
+SYSCALL(link)
+SYSCALL(mkdir)
+SYSCALL(chdir)
+SYSCALL(dup)
+SYSCALL(getpid)
+SYSCALL(sbrk)
+SYSCALL(sleep)
+SYSCALL(uptime)
+SYSCALL(putc)
\ No newline at end of file