Changes in the README, changes to fork template.

tasks/libposix/fork.c

@@ -0,0 +1,46 @@
+/*
+ * l4/posix glue for fork()
+ *
+ * Copyright (C) 2008 Bahadir Balban
+ */
+#include <errno.h>
+#include <stdio.h>
+#include <sys/types.h>
+#include <l4lib/arch/syscalls.h>
+#include <l4lib/arch/syslib.h>
+#include <l4lib/ipcdefs.h>
+#include <l4lib/utcb.h>
+#include <l4/macros.h>
+#include INC_GLUE(memory.h)
+
+static inline int l4_fork(void)
+{
+	int err;
+
+	/* Call pager with open() request. Check ipc error. */
+	if ((err = l4_sendrecv(PAGER_TID, PAGER_TID, L4_IPC_TAG_FORK)) < 0) {
+		printf("%s: L4 IPC Error: %d.\n", __FUNCTION__, err);
+		return err;
+	}
+	/* Check if syscall itself was successful */
+	if ((err = l4_get_retval()) < 0) {
+		printf("%s: OPEN Error: %d.\n", __FUNCTION__, err);
+		return err;
+	}
+	return err;
+}
+
+int fork(void)
+{
+	int ret = l4_fork();
+
+	/* If error, return positive error code */
+	if (ret < 0) {
+		errno = -ret;
+		return -1;
+	}
+	/* else return value */
+	return ret;
+
+}
+

tasks/mm0/include/syscalls.h

@@ -43,5 +43,7 @@ struct sys_shmget_args {
 
 int sys_shmget(key_t key, int size, int shmflg);
 
+int sys_fork(void);
+
 #endif /* __MM0_SYSARGS_H__ */
 

tasks/mm0/main.c

@@ -100,7 +100,7 @@ void handle_requests(void)
 	case L4_IPC_TAG_CLOSE:
 		sys_close(sender, (int)mr[0]);
 		break;
-	
+
 	case L4_IPC_TAG_FSYNC:
 		sys_fsync(sender, (int)mr[0]);
 		break;
@@ -120,6 +120,10 @@ void handle_requests(void)
 			 args->flags, args->fd, __pfn(args->offset));
 		break;
 	}
+	case L4_IPC_TAG_MMAP: {
+		sys_fork(sender);
+		break;
+	}
 	case L4_IPC_TAG_BRK: {
 //		sys_brk(sender, (void *)mr[0]);
 //		break;

tasks/mm0/src/clone.c

@@ -3,7 +3,7 @@
  *
  * Copyright (C) 2008 Bahadir Balban
  */
-
+#include <syscalls.h>
 
 int copy_tcb(struct tcb *p, struct tcb *c)
 {
@@ -28,20 +28,33 @@ int do_fork(struct tcb *parent)
 {
 	struct tcb *child;
 
+	/* Make all parent shadows read only */
+	vm_freeze_shadows(parent);
+
 	/* Create a new L4 thread with new space */
 	l4_thread_create(parent);
 
 	/* Create a new local tcb */
 	child = tcb_alloc_init();
 
-	/* Make all parent shadows read only */
-	vm_freeze_shadows(parent);
-
 	/* Copy parent tcb to child */
 	copy_tcb(struct tcb *parent, struct tcb *child);
 
-	/* FIXME: Copy parent page tables to child ??? */
-	/* FIXME: Copy parent register values to child ??? */
+	/*
+	 * Allocate and copy parent pgd + all pmds to child.
+	 *
+	 * When a write fault occurs on any of the frozen shadows,
+	 * fault handler creates a new shadow on top, if it hasn't,
+	 * and then starts adding writeable pages to the new shadow.
+	 * Every forked task will fault on every page of the frozen shadow,
+	 * until all pages have been made copy-on-write'ed, in which case
+	 * the underlying frozen shadow is collapsed.
+	 *
+	 * Every forked task must have its own copy of pgd + pmds because
+	 * every one of them will have to fault on frozen shadows individually.
+	 */
+
+	/* FIXME: Need to copy parent register values to child ??? */
 
 	/* Notify fs0 about forked process */
 	vfs_send_fork(parent, child);

tasks/test0/main.c

@@ -10,7 +10,8 @@
 #include <l4lib/utcb.h>
 #include <l4lib/ipcdefs.h>
 #include <tests.h>
-
+#include <unistd.h>
+#include <sys/types.h>
 
 void wait_pager(l4id_t partner)
 {
@@ -23,23 +24,32 @@ void wait_pager(l4id_t partner)
 
 void main(void)
 {
+	pid_t pid;
+
 	printf("\n%s: Started with tid %d.\n", __TASKNAME__, self_tid());
 	/* Sync with pager */
 	wait_pager(0);
 
 	dirtest();
-	printf("File IO test 1:\n");
-	if (fileio() == 0)
-		printf("-- PASSED --\n");
-	else
-		printf("-- FAILED --\n");
 
-	printf("File IO test 2:\n");
-	if (fileio2() == 0)
-		printf("-- PASSED --\n");
-	else
-		printf("-- FAILED --\n");
+	printf("Forking...\n");
 
+	if ((pid = fork()) < 0)
+		printf("Error forking...\n");
+
+	if (pid == 0) {
+		printf("File IO test 1, done by child:\n");
+		if (fileio() == 0)
+			printf("-- PASSED --\n");
+		else
+			printf("-- FAILED --\n");
+	} else {
+		printf("File IO test 2, done by parent, with child pid %d:\n", pid);
+		if (fileio2() == 0)
+			printf("-- PASSED --\n");
+		else
+			printf("-- FAILED --\n");
+	}
 	while (1)
 		wait_pager(0);
 #if 0