Remove sys_init syscall

Invoke initlog from forkret on first user process

initcode.S

@@ -7,8 +7,6 @@
 # exec(init, argv)
 .globl start
 start:
-  movl $SYS_init, %eax
-  int $T_SYSCALL
   pushl $argv
   pushl $init
   pushl $0  // where caller pc would be

main.c

@@ -60,7 +60,7 @@ mpmain(void)
   scheduler();     // start running processes
 }
 
-pde_t enterpgdir[];
+pde_t enterpgdir[];  // For entry.S
 
 // Start the non-boot (AP) processors.
 static void

proc.c

@@ -322,8 +322,14 @@ yield(void)
 void
 forkret(void)
 {
+  static int first = 1;
   // Still holding ptable.lock from scheduler.
   release(&ptable.lock);
+
+  if (first) {
+    first = 0;
+    initlog();
+  }
   
   // Return to "caller", actually trapret (see allocproc).
 }

syscall.c

@@ -99,15 +99,7 @@ extern int sys_wait(void);
 extern int sys_write(void);
 extern int sys_uptime(void);
 
-int
-sys_init(void)
-{
-  initlog();
-  return 0;
-}
-
 static int (*syscalls[])(void) = {
-[SYS_init]    sys_init,
 [SYS_fork]    sys_fork,
 [SYS_exit]    sys_exit,
 [SYS_wait]    sys_wait,
@@ -122,7 +114,6 @@ static int (*syscalls[])(void) = {
 [SYS_sbrk]    sys_sbrk,
 [SYS_sleep]   sys_sleep,
 [SYS_uptime]  sys_uptime,
-// File system calls that are run in a transaction:
 [SYS_open]    sys_open,
 [SYS_write]   sys_write,
 [SYS_mknod]   sys_mknod,

syscall.h

 // System call numbers
-#define SYS_init    0
 #define SYS_fork    1
 #define SYS_exit    2
 #define SYS_wait    3