diff --git a/executer/kernel/ikc.c b/executer/kernel/ikc.c
index d571b52f..a2b7f010 100644
--- a/executer/kernel/ikc.c
+++ b/executer/kernel/ikc.c
@@ -43,7 +43,7 @@ static void mcctrl_ikc_init(ihk_os_t os, int cpu, unsigned long rphys, struct ih
 int mcexec_syscall(struct mcctrl_channel *c, int pid, unsigned long arg);
 void procfs_create(void *__os, int ref, int osnum, int pid, unsigned long arg);
 void procfs_delete(void *__os, unsigned long arg);
-void procfs_answer(unsigned long arg);
+void procfs_answer(unsigned long arg, int err);
 
 static int syscall_packet_handler(struct ihk_ikc_channel_desc *c,
                                   void *__packet, void *__os)
@@ -77,7 +77,7 @@ static int syscall_packet_handler(struct ihk_ikc_channel_desc *c,
 		break;
 
 	case SCD_MSG_PROCFS_ANSWER:
-		procfs_answer(pisp->arg);
+		procfs_answer(pisp->arg, pisp->err);
 		break;
 	}
 
diff --git a/executer/kernel/procfs.c b/executer/kernel/procfs.c
index b9eb5e80..2eacc10a 100644
--- a/executer/kernel/procfs.c
+++ b/executer/kernel/procfs.c
@@ -17,7 +17,7 @@
 #include <linux/fs.h>
 #include "mcctrl.h"
 
-#define PROCFS_DEBUG
+//#define PROCFS_DEBUG
 
 #ifdef PROCFS_DEBUG
 #define	dprintk(...)	printk(__VA_ARGS__)
@@ -47,9 +47,11 @@ struct procfs_list_entry {
 LIST_HEAD(procfs_file_list);
 static ihk_spinlock_t procfs_file_list_lock;
 
-/*
- * char *p a name of the procfs file
- * int mode if zero create a directory otherwise a file
+/**
+ * \brief Return specified procfs entry. 
+ *
+ * \param p a name of the procfs file
+ * \param mode if zero create a directory otherwise a file
  *
  * return value: NULL: Something wrong has occurred.
  *               otherwise: address of the proc_dir_entry structure of the procfs file
@@ -130,6 +132,16 @@ static struct proc_dir_entry *get_procfs_entry(char *p, int mode)
 	return ret;
 }
 
+/**
+ * \brief Create a procfs entry.
+ *
+ * \param __os (opeque) os variable
+ * \param ref cpuid of the requesting mckernel process
+ * \param osnum osnum of the requesting mckernel process
+ * \param pid pid of the requesting mckernel process
+ * \param arg sent argument
+ */
+
 void procfs_create(void *__os, int ref, int osnum, int pid, unsigned long arg)
 {
 	struct proc_dir_entry *entry;
@@ -175,6 +187,13 @@ quit:
 	dprintk("procfs_create: done\n");
 }
 
+/**
+ * \brief Delete a procfs entry.
+ *
+ * \param __os (opaque) os variable
+ * \param arg sent argument
+ */
+
 void procfs_delete(void *__os, unsigned long arg)
 {
 	ihk_device_t dev = ihk_os_to_dev(__os);
@@ -216,15 +235,22 @@ void procfs_delete(void *__os, unsigned long arg)
 	dprintk("procfs_delete: done\n");
 }
 
-void procfs_answer(unsigned int arg)
+/**
+ * \brief Process SCD_MSG_PROCFS_ANSWER message.
+ *
+ * \param arg sent argument
+ * \param err error info (redundant)
+ */
+
+void procfs_answer(unsigned int arg, int err)
 {
-	dprintk("procfs: received SCD_MSG_PROCFS_ANSWER message.\n");
+	dprintk("procfs: received SCD_MSG_PROCFS_ANSWER message(err = %d).\n", err);
 	procfsq_channel = arg;
 	wake_up_interruptible(&procfsq);
 }
 
-/*
- * callback funciton for McKernel procfs
+/**
+ * \brief The callback funciton for McKernel procfs
  *
  * This function conforms to the 2) way of fs/proc/generic.c
  * from linux-2.6.39.4.
@@ -238,11 +264,10 @@ int mckernel_procfs_read(char *buffer, char **start, off_t offset,
 	struct procfs_list_entry *e = dat;
 	struct procfs_read *r;
 	struct ikc_scd_packet isp;
-	int ret;
+	int ret, retrycount = 0;
 	unsigned long pbuf;
 
 	dprintk("mckernel_procfs_read: invoked for %s\n", e->fname); 
-	dprintk("offset: %lx, count: %d\n", offset, count);
 
 	if (count <= 0 || dat == NULL) {
 		return 0;
@@ -258,9 +283,11 @@ int mckernel_procfs_read(char *buffer, char **start, off_t offset,
 		return -ENOMEM;
 	}
 retry:
+	dprintk("offset: %lx, count: %d, cpu: %d\n", offset, count, e->cpu);
+
 	r->pbuf = pbuf;
 	r->eof = 0;
-	r->ret = 0;
+	r->ret = -EIO;	/* default to error */
 	r->offset = offset;
 	r->count = count;
 	strncpy(r->fname, e->fname, PROCFS_NAME_MAX);
@@ -281,6 +308,10 @@ retry:
 		/* A miss-hit caused by migration has occurred.
 		 * We simply retry the query with a new CPU.
 		 */
+		if (retrycount++ > 10) {
+			kprintf("ERROR: mckernel_procfs_read: excessive retry.\n");
+			return -EIO;
+		}
 		e->cpu = r->newcpu;
 		dprintk("retry\n");
 		goto retry;
@@ -288,10 +319,6 @@ retry:
 	if (r->eof == 1) {
 		*peof = 1;
 	}
-	/* We employ the 2) method for a proc read function.
-	 * Refer to fs/proc/generic.c of the Linux kernel 
-	 * for the details.
-	 */
 	*start = buffer;
 	ret = r->ret;
 	kfree(r);
@@ -299,16 +326,28 @@ retry:
 	return ret;
 }
 
-void procfs_init(int i) {
+/**
+ * \brief Initialization for procfs
+ *
+ * \param osnum os number
+ */
+
+void procfs_init(int osnum) {
 }
 
-void procfs_exit(int i) {
+/**
+ * \brief Finalization for procfs
+ *
+ * \param osnum os number
+ */
+
+void procfs_exit(int osnum) {
 	char buf[20];
 	int error;
 	mm_segment_t old_fs = get_fs();
 	struct kstat stat;
 
-	sprintf(buf, "/proc/mcos%d", i);
+	sprintf(buf, "/proc/mcos%d", osnum);
 
 	set_fs(KERNEL_DS);
 	error = vfs_stat (buf, &stat);
@@ -317,5 +356,6 @@ void procfs_exit(int i) {
 		return;
 	}
 
+	/* remove remnant of previous mcos%d */
 	remove_proc_entry(buf + 6, NULL);
 }
diff --git a/kernel/init.c b/kernel/init.c
index 21799eea..39deea57 100644
--- a/kernel/init.c
+++ b/kernel/init.c
@@ -35,7 +35,7 @@
 #include <ioctl.h>
 #endif
 
-#define DEBUG_PRINT_INIT
+//#define DEBUG_PRINT_INIT
 
 #ifdef DEBUG_PRINT_INIT
 #define dkprintf kprintf
diff --git a/kernel/procfs.c b/kernel/procfs.c
index fbc1dbb0..ca3056fc 100644
--- a/kernel/procfs.c
+++ b/kernel/procfs.c
@@ -24,7 +24,7 @@
 #include <page.h>
 #include <mman.h>
 
-#define DEBUG_PRINT_PROCFS
+//#define DEBUG_PRINT_PROCFS
 
 #ifdef DEBUG_PRINT_PROCFS
 #define	dprintf(...) kprintf(__VA_ARGS__)
@@ -46,6 +46,13 @@ static void create_proc_procfs_file(int pid, char *fname, int mode, int cpuid);
 static void delete_proc_procfs_file(int pid, char *fname);
 static void operate_proc_procfs_file(int pid, char *fname, int msg, int mode, int cpuid);
 
+/**
+ * \brief Create all procfs files for process.
+ *
+ * \param pid pid of the process
+ * \param cpuid cpuid of the process
+ */
+
 void create_proc_procfs_files(int pid, int cpuid)
 {
 	char fname[PROCFS_NAME_MAX];
@@ -58,12 +65,27 @@ void create_proc_procfs_files(int pid, int cpuid)
 	dprintf("create procfs files: done\n");
 }
 
+/**
+ * \brief Create a procfs file for process.
+ *
+ * \param pid pid of the process
+ * \param fname file name of the procfs file
+ * \param mode file mode
+ * \param cpuid cpuid of the process
+ */
+
 static void create_proc_procfs_file(int pid, char *fname, int mode, int cpuid)
 {
 	dprintf("create procfs file: %s, mode: %o, cpuid: %d\n", fname, mode, cpuid);
 	operate_proc_procfs_file(pid, fname, SCD_MSG_PROCFS_CREATE, mode, cpuid);
 }
 
+/**
+ * \brief Delete all procfs files for process.
+ *
+ * \param pid pid of the process
+ */
+
 void delete_proc_procfs_files(int pid)
 {
 	char fname[PROCFS_NAME_MAX];
@@ -89,6 +111,13 @@ void delete_proc_procfs_files(int pid)
 	dprintf("delete procfs files: done\n");
 }
 
+/**
+ * \brief Delete a procfs file for process.
+ *
+ * \param pid pid of the process
+ * \param fname file name of the procfs file
+ */
+
 static void delete_proc_procfs_file(int pid, char *fname)
 {
 	dprintf("delete procfs file: %s\n", fname);
@@ -96,6 +125,16 @@ static void delete_proc_procfs_file(int pid, char *fname)
 	dprintf("delete procfs file: %s done\n", fname);
 }
 
+/**
+ * \brief Create/delete a procfs file for process.
+ *
+ * \param pid pid of the process
+ * \param fname file name of the procfs file
+ * \param msg message (create/delete) 
+ * \param mode file mode
+ * \param cpuid cpuid of the process
+ */
+
 static void operate_proc_procfs_file(int pid, char *fname, int msg, int mode, int cpuid)
 {
 	struct ihk_ikc_channel_desc *syscall_channel;
@@ -132,89 +171,165 @@ static void operate_proc_procfs_file(int pid, char *fname, int msg, int mode, in
 	kfree(f);
 }
 
+/**
+ * \brief The callback function for mckernel procfs files.
+ *
+ * \param rarg returned argument
+ */
+
 void process_procfs_request(unsigned long rarg)
 {
 	unsigned long parg, pbuf;
         struct process *proc = cpu_local_var(current);
 	struct procfs_read *r;
 	struct ikc_scd_packet packet;
-	int rosnum, ret, pid, tid, ans = -ENOENT, eof = 0;
-	char *buf;
+	int rosnum, ret, pid, tid, ans = -EIO, eof = 0;
+	char *buf, *p;
 	struct ihk_ikc_channel_desc *syscall_channel;
 
 	dprintf("process_procfs_request: invoked.\n");
 
 	syscall_channel = get_cpu_local_var(0)->syscall_channel;
 
+	dprintf("rarg: %x\n", rarg);
 	parg = ihk_mc_map_memory(NULL, rarg, sizeof(struct procfs_read));
+	dprintf("parg: %x\n", parg);
 	r = ihk_mc_map_virtual(parg, sizeof(struct procfs_read), 
 			       PTATTR_WRITABLE | PTATTR_ACTIVE);
+	dprintf("r: %p\n", r);
+	if (r == NULL) {
+		kprintf("ERROR: process_procfs_request: got a null procfs_read structure.\n");
+		packet.err = -EIO;
+		goto dataunavail;
+	}
 
+	dprintf("remote pbuf: %x\n", r->pbuf);
 	pbuf = ihk_mc_map_memory(NULL, r->pbuf, r->count);
+	dprintf("pbuf: %x\n", pbuf);
 	buf = ihk_mc_map_virtual(pbuf, r->count, PTATTR_WRITABLE | PTATTR_ACTIVE);
+	dprintf("buf: %p\n", buf);
+	if (buf == NULL) {
+		kprintf("ERROR: process_procfs_request: got a null buffer.\n");
+		packet.err = -EIO;
+		goto bufunavail;
+	}
 
 	dprintf("fname: %s, offset: %lx, count:%d.\n", r->fname, r->offset, r->count);
 
-	/* mcos0/PID/taks/PID/mem
-	 *
-	 * The offset is treated as the beginning of the virtual address area
-	 * of the process. The count is the length of the area.
+	/*
+	 * check for "mcos%d/"
 	 */
-	ret = sscanf(r->fname, "mcos%d/%d/task/%d/mem", &rosnum, &pid, &tid);
-	if ((ret == 3) && (pid == tid) && (osnum == rosnum)) {
-		if (cpu_local_var(current)->pid != pid) {
-			/* The target process has gone by migration. */
-#ifdef FIXME
-			r->newcpu = ...
-#endif
-			ans = 0;
-		} else {
-			struct vm_range *range;
-			struct process_vm *vm = proc->vm;
-			ans = -EIO; /* default to an I/O error */
-			list_for_each_entry(range, &vm->vm_range_list, list) {
-				dprintf("range: %lx - %lx\n", range->start, range->end);
-				if ((range->start <= r->offset) && 
-				    (r->offset < range->end)) {
-					unsigned int len = r->count;
-					if (range->end < r->offset + r->count) {
-						len = range->end - r->offset;
-					}
-					memcpy((void *) buf, (void *)range->start, len);
-					ans = len;
-					break;
-				}
-			}
+	ret = sscanf(r->fname, "mcos%d/", &rosnum);
+	if (ret == 1) {
+		if (osnum != rosnum) {
+			kprintf("ERROR: process_procfs_request osnum mismatch "
+				"(we are %d != requested %d)\n",
+				osnum, rosnum);
+			goto end;
 		}
+		dprintf("matched mcos%d.\n", osnum);
+	} else {
 		goto end;
 	}
+	p = strchr(r->fname, '/') + 1;
 
-	/* Processing of other kinds of procfs files should be located here.
+	/* Processing for pattern "mcos%d/xxx" files should be here.
 	   Its template is something like what follows:
 
-	   ret = scanf(r->fname, "mcos%d/PATTERN", ...)
-	   if ((ret == x) && pattern has matched) {
-	   	get the data and write it to the buffer;
+	   ret = sscanf(p, "PATTERN", ...)
+	   if ((ret == xx) && pattern has matched) {
+	   	   get the data (at 'r->offset')
+		   and write it to 'buf'
+		   up to 'r->count' bytes.
 		ans = written bytes;
 		goto end;
 	   }
 	*/
 
+	/*
+	 * check for "mcos%d/PID/"
+	 */
+	ret = sscanf(p, "%d/", &pid);
+	if (ret == 1) {
+		if (pid != cpu_local_var(current)->pid) {
+			/* We are not located in the proper cpu for some reason. */
+			void *savelock;
+			unsigned long irqstate;
+			struct process *proc;
+
+			dprintf("mismatched pid. We are %d, but requested pid is %d.\n",
+				pid, cpu_local_var(current)->pid);
+			if ((proc = findthread_and_lock(pid, tid, &savelock, &irqstate))){
+				/* The target process has gone by migration. */
+				r->newcpu = proc->cpu_id;
+				dprintf("expected cpu id is %d.\n", proc->cpu_id);
+				process_unlock(savelock, irqstate);
+				ans = 0;
+			} else {
+				dprintf("We cannot find the proper cpu for requested pid.\n");
+			}
+			goto end;
+		}
+	} else {
+		goto end;
+	}
+	dprintf("matched PID: %d.\n", pid);
+	p = strchr(p, '/') + 1;
+
+	/* 
+	 * mcos0/PID/taks/PID/mem
+	 *
+	 * The offset is treated as the beginning of the virtual address area
+	 * of the process. The count is the length of the area.
+	 */
+	ret = sscanf(p, "task/%d/mem", &tid);
+	if (ret == 1) {
+		struct vm_range *range;
+		struct process_vm *vm = proc->vm;
+
+		if (pid != tid) {
+			/* We are not multithreaded yet. */
+			goto end;
+		} 
+		list_for_each_entry(range, &vm->vm_range_list, list) {
+			dprintf("range: %lx - %lx\n", range->start, range->end);
+			if ((range->start <= r->offset) && 
+			    (r->offset < range->end)) {
+				unsigned int len = r->count;
+				if (range->end < r->offset + r->count) {
+					len = range->end - r->offset;
+				}
+				memcpy((void *) buf, (void *)range->start, len);
+				ans = len;
+				break;
+			}
+		}
+		goto end;
+	}
+
+	/* 
+	 * Processing for pattern "mcos%d/PID/xxx" files should be here.
+	*/
+	dprintf("could not find a matching entry for %s.\n", p); 
 end:
-	dprintf("read: %d, eof: %d\n", ans, eof);
+	ihk_mc_unmap_virtual(buf, r->count, 0);
+	dprintf("ret: %d, eof: %d\n", ans, eof);
 	r->ret = ans;
 	r->eof = eof;
+	packet.err = 0;
+bufunavail:
+	ihk_mc_unmap_memory(NULL, pbuf, r->count);
+	ihk_mc_unmap_virtual(r, sizeof(struct procfs_read), 0);
+dataunavail:
+	ihk_mc_unmap_memory(NULL, parg, sizeof(struct procfs_read));
+
 	packet.msg = SCD_MSG_PROCFS_ANSWER;
 	packet.arg = rarg;
-	
-	ihk_mc_unmap_virtual(buf, r->count, 0);
-	ihk_mc_unmap_memory(NULL, pbuf, r->count);
-
-	ihk_mc_unmap_virtual(r, sizeof(struct procfs_read), 0);
-	ihk_mc_unmap_memory(NULL, parg, sizeof(struct procfs_read));
 
 	ret = ihk_ikc_send(syscall_channel, &packet, 0);
 	if (ret < 0) {
 		kprintf("ERROR: sending IKC msg, ret: %d\n", ret);
 	}
+	return;
+
 }
diff --git a/lib/include/string.h b/lib/include/string.h
index e34afe58..0c10d1af 100644
--- a/lib/include/string.h
+++ b/lib/include/string.h
@@ -22,6 +22,7 @@ char *strncpy(char *dest, const char *src, size_t maxlen);
 int strcmp(const char *s1, const char *s2);
 int strncmp(const char *s1, const char *s2, size_t n);
 char *strstr(const char *haystack, const char *needle);
+char *strchr(const char *s, int n);
 void *memcpy(void *dest, const void *src, size_t n);
 void *memcpy_long(void *dest, const void *src, size_t n);
 int memcmp(const void *s1, const void *s2, size_t n);
diff --git a/lib/string.c b/lib/string.c
index 41f58a40..4509630c 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -80,6 +80,21 @@ int strncmp(const char *s1, const char *s2, size_t n)
 	return *s1 - *s2;
 }
 
+char *strchr(const char *s, int n) {
+	char *p = (char *)s; 
+	while (1) {
+		if (*p == n)
+		{
+			return p;
+		} else if (*p == '\0') {
+			break;
+		}
+		++p;
+	}
+	return NULL;
+}
+		
+
 char *strstr(const char *haystack, const char *needle)
 {
 	int len = strlen(needle);