diff --git a/boot/boot.c b/boot/boot.c
index 3b3497eea..2f30fa172 100644
--- a/boot/boot.c
+++ b/boot/boot.c
@@ -743,7 +743,7 @@ static void sfree(char *s)
 	if (s != nil && s != null) free(s);
 }
 
-static char *copystr(char *s)
+static char *copystr(const char *s)
 /* Copy a non-null string using malloc. */
 {
 	char *c;
@@ -754,12 +754,12 @@ static char *copystr(char *s)
 	return c;
 }
 
-static int is_default(environment *e)
+static int is_default(const environment *e)
 {
 	return (e->flags & E_SPECIAL) && e->defval == nil;
 }
 
-static environment **searchenv(char *name)
+static environment **searchenv(const char *name)
 {
 	environment **aenv= &env;
 
@@ -1538,7 +1538,7 @@ int expired(void)
 	return (Thandler != nil && milli_since(Tbase) >= Tcount);
 }
 
-void delay(char *msec)
+void delay(const char *msec)
 /* Delay for a given time. */
 {
 	u32_t base, count;
@@ -1553,7 +1553,7 @@ void delay(char *msec)
 	} while (!interrupt() && !expired() && milli_since(base) < count);
 }
 
-static enum whatfun { NOFUN, SELECT, DEFFUN, USERFUN } menufun(environment *e)
+static enum whatfun { NOFUN, SELECT, DEFFUN, USERFUN } menufun(const environment *e)
 {
 	if (!(e->flags & E_FUNCTION) || e->arg[0] == 0) return NOFUN;
 	if (e->arg[1] != ',') return SELECT;
diff --git a/boot/boot.h b/boot/boot.h
index 3aa625139..51ae27939 100644
--- a/boot/boot.h
+++ b/boot/boot.h
@@ -213,7 +213,7 @@ EXTERN char *drun;	/* Initial command from DOS command line. */
 #endif
 
 void readblock(off_t, char *, int);
-void delay(char *);
+void delay(const char *);
 
 /*
  * $PchId: boot.h,v 1.12 2002/02/27 19:42:45 philip Exp $
diff --git a/boot/bootimage.c b/boot/bootimage.c
index a224ccba9..6c3ab3590 100644
--- a/boot/bootimage.c
+++ b/boot/bootimage.c
@@ -84,7 +84,7 @@ int n_procs;			/* Number of processes. */
 
 #define between(a, c, z)	((unsigned) ((c) - (a)) <= ((z) - (a)))
 
-void pretty_image(char *image)
+void pretty_image(const char *image)
 /* Pretty print the name of the image to load.  Translate '/' and '_' to
  * space, first letter goes uppercase.  An 'r' before a digit prints as
  * 'revision'.  E.g. 'minix/1.6.16r10' -> 'Minix 1.6.16 revision 10'.
@@ -234,7 +234,7 @@ void patch_sizes(void)
 	put_word(process[FS].data + P_INIT_OFF+4, data_size);
 }
 
-int selected(char *name)
+int selected(const char *name)
 /* True iff name has no label or the proper label. */
 {
 	char *colon, *label;
@@ -249,7 +249,7 @@ int selected(char *name)
 	return cmp == 0;
 }
 
-u32_t proc_size(struct image_header *hdr)
+static u32_t proc_size(const struct image_header *hdr)
 /* Return the size of a process in sectors as found in an image. */
 {
 	u32_t len= hdr->process.a_text;
diff --git a/boot/installboot.c b/boot/installboot.c
index ccaf31dea..29e53a3d4 100644
--- a/boot/installboot.c
+++ b/boot/installboot.c
@@ -40,13 +40,13 @@
 
 #define BOOT_BLOCK_SIZE 1024
 
-void report(char *label)
+static void report(const char *label)
 /* installboot: label: No such file or directory */
 {
 	fprintf(stderr, "installboot: %s: %s\n", label, strerror(errno));
 }
 
-void fatal(char *label)
+static void fatal(const char *label)
 {
 	report(label);
 	exit(1);
@@ -75,7 +75,7 @@ char *basename(char *name)
 	return base;
 }
 
-void bread(FILE *f, char *name, void *buf, size_t len)
+static void bread(FILE *f, char *name, void *buf, size_t len)
 /* Read len bytes.  Don't dare return without them. */
 {
 	if (len > 0 && fread(buf, len, 1, f) != 1) {
@@ -85,7 +85,7 @@ void bread(FILE *f, char *name, void *buf, size_t len)
 	}
 }
 
-void bwrite(FILE *f, char *name, void *buf, size_t len)
+static void bwrite(FILE *f, char *name, const void *buf, size_t len)
 {
 	if (len > 0 && fwrite(buf, len, 1, f) != 1) fatal(name);
 }
@@ -351,7 +351,7 @@ void readblock(off_t blk, char *buf, int block_size)
 	}
 }
 
-void writeblock(off_t blk, char *buf, int block_size)
+void writeblock(off_t blk, const char *buf, int block_size)
 /* Add a function to write blocks for local use. */
 {
 	if (lseek(rawfd, blk * block_size, SEEK_SET) < 0
@@ -685,7 +685,7 @@ void make_bootable(enum howto how, char *device, char *bootblock,
 	}
 }
 
-void install_master(char *device, char *masterboot, char **guide)
+static void install_master(char *device, char *masterboot, char **guide)
 /* Booting a hard disk is a two stage process:  The master bootstrap in sector
  * 0 loads the bootstrap from sector 0 of the active partition which in turn
  * starts the operating system.  This code installs such a master bootstrap
@@ -727,8 +727,8 @@ void install_master(char *device, char *masterboot, char **guide)
 
 	if (guide[0] != nil) {
 		/* Fixate partition to boot. */
-		char *keys= guide[0];
-		char *logical= guide[1];
+		const char *keys= guide[0];
+		const char *logical= guide[1];
 		size_t i;
 		int logfd;
 		u32_t offset;
@@ -782,7 +782,7 @@ void install_master(char *device, char *masterboot, char **guide)
 	writeblock(BOOTBLOCK, buf, BOOT_BLOCK_SIZE);
 }
 
-void usage(void)
+static void usage(void)
 {
 	fprintf(stderr,
 	  "Usage: installboot -i(mage) image kernel mm fs ... init\n"
@@ -793,7 +793,7 @@ void usage(void)
 	exit(1);
 }
 
-int isoption(char *option, char *test)
+static int isoption(const char *option, char *test)
 /* Check if the option argument is equals "test".  Also accept -i as short
  * for -image, and the special case -x for -extract.
  */
diff --git a/boot/rawfs.c b/boot/rawfs.c
index a143dc8ff..e77ca35e9 100644
--- a/boot/rawfs.c
+++ b/boot/rawfs.c
@@ -286,7 +286,7 @@ off_t r_vir2abs(off_t virblk)
 	return z;
 }
 
-ino_t r_lookup(Ino_t cwd, char *path)
+ino_t r_lookup(Ino_t cwd, const char *path)
 /* Translates a pathname to an inode number.  This is just a nice utility
  * function, it only needs r_stat and r_readdir.
  */
diff --git a/boot/rawfs.h b/boot/rawfs.h
index ccab56828..a177b7475 100644
--- a/boot/rawfs.h
+++ b/boot/rawfs.h
@@ -17,7 +17,7 @@
  *			Return next directory entry or 0 if there are no more.
  *			Returns -1 and sets errno on error.
  *
- *		ino_t r_lookup(ino_t cwd, char *path);
+ *		ino_t r_lookup(ino_t cwd, const char *path);
  *			A utility function that translates a pathname to an
  *			inode number.  It starts from directory "cwd" unless
  *			path starts with a '/', then from ROOT_INO.
@@ -39,7 +39,7 @@ extern off_t r_super(int *);
 extern void r_stat(Ino_t file, struct stat *stp);
 extern off_t r_vir2abs(off_t virblockno);
 extern ino_t r_readdir(char *name);
-extern ino_t r_lookup(Ino_t cwd, char *path);
+extern ino_t r_lookup(Ino_t cwd, const char *path);
 
 /*
  * $PchId: rawfs.h,v 1.4 1996/04/19 08:16:36 philip Exp $
diff --git a/commands/ash/alias.c b/commands/ash/alias.c
index 90ef85ba0..5a8a3c1cf 100644
--- a/commands/ash/alias.c
+++ b/commands/ash/alias.c
@@ -57,7 +57,7 @@ STATIC struct alias *atab[ATABSIZE];
 
 STATIC void setalias(char *, char *);
 STATIC int unalias(char *);
-STATIC struct alias **hashalias(char *);
+STATIC struct alias **hashalias(const char *);
 
 STATIC
 void
@@ -250,7 +250,7 @@ unaliascmd(int argc __unused, char **argv __unused)
 }
 
 STATIC struct alias **
-hashalias(char *p)
+hashalias(const char *p)
 {
 	unsigned int hashval;
 
diff --git a/commands/ash/cd.c b/commands/ash/cd.c
index e54289d7c..055cb75a0 100644
--- a/commands/ash/cd.c
+++ b/commands/ash/cd.c
@@ -68,10 +68,10 @@ __FBSDID("$FreeBSD: src/bin/sh/cd.c,v 1.34 2004/04/06 20:06:51 markm Exp $");
 #include "cd.h"
 
 STATIC int cdlogical(char *);
-STATIC int cdphysical(char *);
+STATIC int cdphysical(const char *);
 STATIC int docd(char *, int, int);
 STATIC char *getcomponent(void);
-STATIC int updatepwd(char *);
+STATIC int updatepwd(const char *);
 
 STATIC char *curdir = NULL;	/* current working directory */
 STATIC char *prevdir;		/* previous working directory */
@@ -212,7 +212,7 @@ cdlogical(char *dest)
 }
 
 STATIC int
-cdphysical(char *dest)
+cdphysical(const char *dest)
 {
 
 	INTOFF;
@@ -255,7 +255,7 @@ getcomponent(void)
  * that the current directory has changed.
  */
 STATIC int
-updatepwd(char *dir)
+updatepwd(const char *dir)
 {
 	char *new;
 	char *p;
diff --git a/commands/awk/b.c b/commands/awk/b.c
index a4a46acbf..75c6992be 100644
--- a/commands/awk/b.c
+++ b/commands/awk/b.c
@@ -378,7 +378,7 @@ void cfoll(fa *f, Node *v)	/* enter follow set of each leaf of vertex v into lfo
 	}
 }
 
-int first(Node *p)	/* collects initially active leaves of p into setvec */
+int first(const Node *p)	/* collects initially active leaves of p into setvec */
 			/* returns 0 if p matches empty string */
 {
 	int b, lp;
diff --git a/commands/awk/proto.h b/commands/awk/proto.h
index 0a68b3a81..359ae64c9 100644
--- a/commands/awk/proto.h
+++ b/commands/awk/proto.h
@@ -48,7 +48,7 @@ extern	int	quoted(char **);
 extern	char	*cclenter(const char *);
 extern	void	overflo(const char *);
 extern	void	cfoll(fa *, Node *);
-extern	int	first(Node *);
+extern	int	first(const Node *);
 extern	void	follow(Node *);
 extern	int	member(int, const char *);
 extern	int	match(fa *, const char *);
@@ -97,12 +97,12 @@ extern	void	syminit(void);
 extern	void	arginit(int, char **);
 extern	void	envinit(char **);
 extern	Array	*makesymtab(int);
-extern	void	freesymtab(Cell *);
-extern	void	freeelem(Cell *, const char *);
+extern	void	freesymtab(const Cell *);
+extern	void	freeelem(const Cell *, const char *);
 extern	Cell	*setsymtab(const char *, const char *, double, unsigned int, Array *);
 extern	int	hash(const char *, int);
 extern	void	rehash(Array *);
-extern	Cell	*lookup(const char *, Array *);
+extern	Cell	*lookup(const char *, const Array *);
 extern	double	setfval(Cell *, double);
 extern	void	funnyvar(Cell *, const char *);
 extern	char	*setsval(Cell *, const char *);
diff --git a/commands/awk/tran.c b/commands/awk/tran.c
index c19ce9430..57dd281b3 100644
--- a/commands/awk/tran.c
+++ b/commands/awk/tran.c
@@ -154,7 +154,7 @@ Array *makesymtab(int n)	/* make a new symbol table */
 	return(ap);
 }
 
-void freesymtab(Cell *ap)	/* free a symbol table */
+void freesymtab(const Cell *ap)	/* free a symbol table */
 {
 	Cell *cp, *temp;
 	Array *tp;
@@ -182,7 +182,8 @@ void freesymtab(Cell *ap)	/* free a symbol table */
 	free(tp);
 }
 
-void freeelem(Cell *ap, const char *s)	/* free elem s from ap (i.e., ap["s"] */
+void freeelem(const Cell *ap, const char *s)
+/* free elem s from ap (i.e., ap["s"] */
 {
 	Array *tp;
 	Cell *p, *prev = NULL;
@@ -266,7 +267,7 @@ void rehash(Array *tp)	/* rehash items in small table into big one */
 	tp->size = nsz;
 }
 
-Cell *lookup(const char *s, Array *tp)	/* look for s in tp */
+Cell *lookup(const char *s, const Array *tp)	/* look for s in tp */
 {
 	Cell *p;
 	int h;
@@ -359,7 +360,8 @@ Awkfloat getfval(Cell *vp)	/* get float val of a Cell */
 	return(vp->fval);
 }
 
-static char *get_str_val(Cell *vp, char **fmt)        /* get string val of a Cell */
+static char *get_str_val(Cell *vp, char **fmt)
+/* get string val of a Cell */
 {
 	char s[100];	/* BUG: unchecked */
 	double dtemp;
diff --git a/commands/simple/add_route.c b/commands/simple/add_route.c
index cc7380c4f..738952126 100644
--- a/commands/simple/add_route.c
+++ b/commands/simple/add_route.c
@@ -28,8 +28,8 @@ static char *prog_name;
 static enum { ADD, DEL } action;
 
 static void usage(void);
-static int name_to_ip(char *name, ipaddr_t *addr);
-static int parse_cidr(char *cidr, ipaddr_t *addr, ipaddr_t *mask);
+static int name_to_ip(const char *name, ipaddr_t *addr);
+static int parse_cidr(const char *cidr, ipaddr_t *addr, ipaddr_t *mask);
 
 int main(int argc, char *argv[])
 {
@@ -297,7 +297,7 @@ static void usage(void)
 	exit(1);
 }
 
-static int name_to_ip(char *name, ipaddr_t *addr)
+static int name_to_ip(const char *name, ipaddr_t *addr)
 {
 	/* Translate a name to an IP address.  Try first with inet_aton(), then
 	 * with gethostbyname().  (The latter can also recognize an IP address,
@@ -314,7 +314,7 @@ static int name_to_ip(char *name, ipaddr_t *addr)
 	return 1;
 }
 
-static int parse_cidr(char *cidr, ipaddr_t *addr, ipaddr_t *mask)
+static int parse_cidr(const char *cidr, ipaddr_t *addr, ipaddr_t *mask)
 {
 	char *slash, *check;
 	ipaddr_t a;
diff --git a/commands/simple/arp.c b/commands/simple/arp.c
index aef07c26f..7304f15ca 100644
--- a/commands/simple/arp.c
+++ b/commands/simple/arp.c
@@ -43,7 +43,7 @@ static void delete(char *hostname);
 static void do_set(char *hostname, char *ethername, int temp, int pub,
 	int optdelete);
 static ipaddr_t nametoipaddr(char *hostname);
-static void fatal(char *fmt, ...);
+static void fatal(const char *fmt, ...);
 static void usage(void);
 
 int main(int argc, char *argv[])
@@ -444,7 +444,7 @@ static char *ether_ntoa(struct ether_addr *eap)
 }
 #endif
 
-static void fatal(char *fmt, ...)
+static void fatal(const char *fmt, ...)
 {
 	va_list ap;
 
diff --git a/commands/simple/cat.c b/commands/simple/cat.c
index a16af02c1..6ed99a018 100644
--- a/commands/simple/cat.c
+++ b/commands/simple/cat.c
@@ -21,7 +21,7 @@ static char obuf[CHUNK_SIZE];
 static char *op = obuf;
 
 static void copyout(const char *file, int fd);
-static void output(char *buf, size_t count);
+static void output(const char *buf, size_t count);
 static void report(const char *label);
 static void fatal(const char *label);
 
@@ -103,7 +103,7 @@ static void copyout(const char *file, int fd)
   }
 }
 
-static void output(char *buf, size_t count)
+static void output(const char *buf, size_t count)
 {
   ssize_t n;
 
diff --git a/commands/simple/chmod.c b/commands/simple/chmod.c
index f37f718ab..1707a91f8 100644
--- a/commands/simple/chmod.c
+++ b/commands/simple/chmod.c
@@ -39,13 +39,11 @@ int rflag, errors;
 struct stat st;
 char path[PATH_MAX + 1];
 
-_PROTOTYPE(int main, (int argc, char **argv));
-_PROTOTYPE(mode_t parsemode, (char *symbolic, mode_t oldmode));
 _PROTOTYPE(int do_change, (char *name));
 _PROTOTYPE(void usage, (void));
 
 /* Parse a P1003.2 4.7.7-conformant symbolic mode. */
-mode_t parsemode(char *symbolic, mode_t oldmode)
+mode_t parsemode(const char *symbolic, mode_t oldmode)
 {
   mode_t who, mask, newmode, tmpmask;
   char action;
@@ -160,9 +158,7 @@ mode_t parsemode(char *symbolic, mode_t oldmode)
 /* Main module. The single option possible (-R) does not warrant a call to
  * the getopt() stuff.
  */
-int main(argc, argv)
-int argc;
-char *argv[];
+int main(int argc, char *argv[])
 {
   int ex_code = 0;
 
diff --git a/commands/simple/cleantmp.c b/commands/simple/cleantmp.c
index b98c547a1..a0d403e73 100644
--- a/commands/simple/cleantmp.c
+++ b/commands/simple/cleantmp.c
@@ -83,7 +83,7 @@ void days2time(unsigned long days, time_t *retired, time_t *dotretired)
 char *path;	/* Path name constructed in path[]. */
 int plen= 0, pidx= 0;	/* Lenght/index for path[]. */
 
-void addpath(int *didx, char *name)
+void addpath(int *didx, const char *name)
 /* Add a component to path. (name may also be a full path at the first call)
  * The index where the current path ends is stored in *pdi.
  */
@@ -171,7 +171,7 @@ struct file *shorten(struct file *list)
 struct file *ignore_list[1024];
 size_t n_ignored= 0;
 
-unsigned ihash(char *name)
+unsigned ihash(const char *name)
 /* A simple hashing function on a file name. */
 {
 	unsigned h= 0;
diff --git a/commands/simple/cp.c b/commands/simple/cp.c
index 0439748eb..d4e8745d1 100644
--- a/commands/simple/cp.c
+++ b/commands/simple/cp.c
@@ -238,7 +238,7 @@ int writable(const struct stat *stp)
 #define PATH_MAX	1024
 #endif
 
-static char *link_islink(struct stat *stp, const char *file)
+static char *link_islink(const struct stat *stp, const char *file)
 {
     /* Tell if a file, which stat(2) information in '*stp', has been seen
      * earlier by this function under a different name.  If not return a
@@ -347,7 +347,7 @@ static char *link_islink(struct stat *stp, const char *file)
 }
 
 int trylink(const char *src, const char *dst, struct stat *srcst,
-			struct stat *dstst)
+			const struct stat *dstst)
 /* Keep the link structure intact if src has been seen before. */
 {
     char *olddst;
@@ -679,7 +679,7 @@ void copy1(const char *src, const char *dst, struct stat *srcst,
     }
 }
 
-void remove1(const char *src, struct stat *srcst)
+void remove1(const char *src, const struct stat *srcst)
 {
     if (iflag || (!fflag && !writable(srcst))) {
 	fprintf(stderr, "Remove %s? (mode = %03o) ", src,
@@ -693,8 +693,8 @@ void remove1(const char *src, struct stat *srcst)
     }
 }
 
-void link1(const char *src, const char *dst, struct stat *srcst,
-			    struct stat *dstst)
+void link1(const char *src, const char *dst, const struct stat *srcst,
+			    const struct stat *dstst)
 {
     pathname_t sym;
     const char *p;
diff --git a/commands/simple/df.c b/commands/simple/df.c
index 823127960..908b58a10 100644
--- a/commands/simple/df.c
+++ b/commands/simple/df.c
@@ -55,7 +55,7 @@ struct mtab {	/* List of mounted devices from /etc/mtab. */
 } *mtab= NULL;
 
 struct mtab *searchtab(char *name);
-void readmtab(char *type);
+static void readmtab(const char *type);
 int df(const struct mtab *mt);
 bit_t bit_count(unsigned blocks, bit_t bits, int fd, int bs);
 
@@ -132,7 +132,7 @@ Filesystem          Files       Free       Used    % BUsed%   Mounted on"
   exit(ex);
 }
 
-void readmtab(char *type)
+static void readmtab(const char *type)
 /* Turn the mounted file table into a list. */
 {
   struct mtab **amt= &mtab, *new;
diff --git a/commands/simple/du.c b/commands/simple/du.c
index 2803740d5..3e26ede44 100644
--- a/commands/simple/du.c
+++ b/commands/simple/du.c
@@ -138,7 +138,7 @@ nlink_t nlink;
   return(0);
 }
 
-int get_block_size(char *dir, struct stat *st)
+int get_block_size(const char *dir, const struct stat *st)
 {
   struct statfs stfs;
   static int fs_block_size = -1, fs_dev = -1;
diff --git a/commands/simple/fix.c b/commands/simple/fix.c
index 46541f746..af04cd60e 100644
--- a/commands/simple/fix.c
+++ b/commands/simple/fix.c
@@ -38,18 +38,15 @@
 
 char *prog = 0, *processing = 0;
 
-_PROTOTYPE(int main, (int argc, char **argv));
 _PROTOTYPE(char *getline, (FILE *fp, char *b));
 _PROTOTYPE(char *range, (char *s, int *p1, int *p2));
 _PROTOTYPE(int getcommand, (FILE *fp, int *o1, int *o2, char *pcmd, int *n1, int *n2));
-_PROTOTYPE(void fatal, (char *s, ...));
+_PROTOTYPE(void fatal, (const char *s, ...));
 _PROTOTYPE(int strwcmp, (char *s1, char *s2));
 _PROTOTYPE(int whitespace, (int ch));
 
 char *
- getline(fp, b)
-FILE *fp;
-char *b;
+getline(FILE *fp, char *b)
 {
   if (fgets(b, LINELEN, fp) == NULL) fatal("unexpected eof");
 
@@ -58,9 +55,7 @@ char *b;
 
 #define copy(str) printf("%s", str)
 
-int main(argc, argv)
-int argc;
-char **argv;
+int main(int argc, char **argv)
 {
   char cmd, *fl, *fd, obuf[LINELEN], nbuf[LINELEN];
   int o1, o2, n1, n2, here;
@@ -155,7 +150,7 @@ char *pcmd;
 }
 
 #ifdef __STDC__
-void fatal(char *s, ...)
+void fatal(const char *s, ...)
 {
   va_list args;
 
@@ -169,7 +164,7 @@ void fatal(char *s, ...)
 #else
 /* the K&R lib does not have vfprintf */
 void fatal(s, a)
-char *s, *a;
+const char *s, *a;
 {
   fprintf(stderr, "%s: processing: %s fatal: ", prog, processing);
   fprintf(stderr, s, a);
diff --git a/commands/simple/getty.c b/commands/simple/getty.c
index 42d931f35..d4feb4541 100644
--- a/commands/simple/getty.c
+++ b/commands/simple/getty.c
@@ -47,7 +47,7 @@ char *tty_name;			/* name of the line */
 /* Crude indication of a tty being physically secure: */
 #define securetty(dev)		((unsigned) ((dev) - 0x0400) < (unsigned) 8)
 
-void std_out(char *s)
+void std_out(const char *s)
 {
   write(1, s, strlen(s));
 }
diff --git a/kernel/arch/i386/apic.c b/kernel/arch/i386/apic.c
index b5fa1a26f..1547ecca3 100644
--- a/kernel/arch/i386/apic.c
+++ b/kernel/arch/i386/apic.c
@@ -167,12 +167,12 @@ PUBLIC void apic_calibrate_clocks(void)
 	cpu_set_freq(cpuid, cpu_freq);
 }
 
-PRIVATE void lapic_set_timer_one_shot(u32_t value)
+PRIVATE void lapic_set_timer_one_shot(const u32_t value)
 {
 	/* sleep in micro seconds */
 	u32_t lvtt;
 	u32_t ticks_per_us;
-	u8_t cpu = cpuid;
+	const u8_t cpu = cpuid;
 
 	ticks_per_us = lapic_bus_freq[cpu] / 1000000;
 
@@ -187,12 +187,12 @@ PRIVATE void lapic_set_timer_one_shot(u32_t value)
 	lapic_write(LAPIC_TIMER_ICR, value * ticks_per_us);
 }
 
-PUBLIC void lapic_set_timer_periodic(unsigned freq)
+PUBLIC void lapic_set_timer_periodic(const unsigned freq)
 {
 	/* sleep in micro seconds */
 	u32_t lvtt;
 	u32_t lapic_ticks_per_clock_tick;
-	u8_t cpu = cpuid;
+	const u8_t cpu = cpuid;
 
 	lapic_ticks_per_clock_tick = lapic_bus_freq[cpu] / freq;
 
@@ -432,7 +432,7 @@ PRIVATE void lapic_set_dummy_handlers(void)
 #endif
 
 /* Build descriptors for interrupt gates in IDT. */
-PUBLIC void apic_idt_init(int reset)
+PUBLIC void apic_idt_init(const int reset)
 {
 	/* Set up idt tables for smp mode.
 	 */
diff --git a/kernel/arch/i386/breakpoints.c b/kernel/arch/i386/breakpoints.c
index 0e9d40785..176ae609a 100644
--- a/kernel/arch/i386/breakpoints.c
+++ b/kernel/arch/i386/breakpoints.c
@@ -3,7 +3,7 @@
 
 #include "debugreg.h"
 
-int breakpoint_set(phys_bytes linaddr, int bp, int flags)
+int breakpoint_set(phys_bytes linaddr, int bp, const int flags)
 {
 	u32_t dr7, dr7flags;
 	
diff --git a/kernel/arch/i386/clock.c b/kernel/arch/i386/clock.c
index 220d55550..09392c40b 100644
--- a/kernel/arch/i386/clock.c
+++ b/kernel/arch/i386/clock.c
@@ -33,7 +33,7 @@ PRIVATE irq_hook_t pic_timer_hook;		/* interrupt handler hook */
 /*===========================================================================*
  *				init_8235A_timer			     *
  *===========================================================================*/
-PUBLIC int init_8253A_timer(unsigned freq)
+PUBLIC int init_8253A_timer(const unsigned freq)
 {
 	/* Initialize channel 0 of the 8253A timer to, e.g., 60 Hz,
 	 * and register the CLOCK task's interrupt handler to be run
@@ -107,7 +107,7 @@ PUBLIC void arch_stop_local_timer(void)
 	}
 }
 
-PUBLIC int arch_register_local_timer_handler(irq_handler_t handler)
+PUBLIC int arch_register_local_timer_handler(const irq_handler_t handler)
 {
 #ifdef CONFIG_APIC
 	if (lapic_addr) {
diff --git a/kernel/arch/i386/i8259.c b/kernel/arch/i386/i8259.c
index 13e6a867f..4f99bed12 100644
--- a/kernel/arch/i386/i8259.c
+++ b/kernel/arch/i386/i8259.c
@@ -26,7 +26,7 @@
 /*===========================================================================*
  *				intr_init				     *
  *===========================================================================*/
-PUBLIC int intr_init(int mine, int auto_eoi)
+PUBLIC int intr_init(const int mine, const int auto_eoi)
 {
 /* Initialize the 8259s, finishing with all interrupts disabled.  This is
  * only done in protected mode, in real mode we don't touch the 8259s, but
@@ -83,15 +83,15 @@ PUBLIC int intr_disabled(void)
 	return 0;
 }
 
-PUBLIC void irq_8259_unmask(int irq)
+PUBLIC void irq_8259_unmask(const int irq)
 {
-	unsigned ctl_mask = irq < 8 ? INT_CTLMASK : INT2_CTLMASK;
+	const unsigned ctl_mask = irq < 8 ? INT_CTLMASK : INT2_CTLMASK;
 	outb(ctl_mask, inb(ctl_mask) & ~(1 << (irq & 0x7)));
 }
 
-PUBLIC void irq_8259_mask(int irq)
+PUBLIC void irq_8259_mask(const int irq)
 {
-	unsigned ctl_mask = irq < 8 ? INT_CTLMASK : INT2_CTLMASK;
+	const unsigned ctl_mask = irq < 8 ? INT_CTLMASK : INT2_CTLMASK;
 	outb(ctl_mask, inb(ctl_mask) | (1 << (irq & 0x7)));
 }
 
diff --git a/kernel/arch/i386/memory.c b/kernel/arch/i386/memory.c
index 4eaa6d82d..c65dac545 100644
--- a/kernel/arch/i386/memory.c
+++ b/kernel/arch/i386/memory.c
@@ -78,8 +78,8 @@ PUBLIC void vm_init(struct proc *newptproc)
  * for actual use by phys_copy or phys_memset.
  */
 PRIVATE phys_bytes createpde(
-	struct proc *pr,	/* Requested process, NULL for physical. */
-	phys_bytes linaddr,	/* Address after segment translation. */
+	const struct proc *pr,	/* Requested process, NULL for physical. */
+	const phys_bytes linaddr,/* Address after segment translation. */
 	phys_bytes *bytes,	/* Size of chunk, function may truncate it. */
 	int pde,		/* freepde number to use for the mapping. */
 	int *changed		/* If mapping is made, this is set to 1. */
@@ -199,7 +199,7 @@ PRIVATE int lin_lin_copy(struct proc *srcproc, vir_bytes srclinaddr,
 
 PRIVATE u32_t phys_get32(phys_bytes addr)
 {
-	u32_t v;
+	const u32_t v;
 	int r;
 
 	if(!vm_running) {
@@ -285,8 +285,8 @@ PRIVATE void vm_enable_paging(void)
 }
 
 PUBLIC vir_bytes alloc_remote_segment(u32_t *selector,
-	segframe_t *segments, int index, phys_bytes phys, vir_bytes size,
-	int priv)
+	segframe_t *segments, const int index, phys_bytes phys,
+	vir_bytes size, int priv)
 {
 	phys_bytes offset = 0;
 	/* Check if the segment size can be recorded in bytes, that is, check
@@ -309,8 +309,8 @@ PUBLIC vir_bytes alloc_remote_segment(u32_t *selector,
 	return offset;
 }
 
-PUBLIC phys_bytes umap_remote(struct proc* rp, int seg,
-	vir_bytes vir_addr, vir_bytes bytes)
+PUBLIC phys_bytes umap_remote(const struct proc* rp, const int seg,
+	const vir_bytes vir_addr, const vir_bytes bytes)
 {
 /* Calculate the physical memory address for a given virtual address. */
   struct far_mem *fm;
@@ -423,7 +423,8 @@ vir_bytes bytes;                /* # of bytes to be copied */
 /*===========================================================================*
  *                              vm_lookup                                    *
  *===========================================================================*/
-PUBLIC int vm_lookup(struct proc *proc, vir_bytes virtual, vir_bytes *physical, u32_t *ptent)
+PUBLIC int vm_lookup(const struct proc *proc, const vir_bytes virtual,
+ vir_bytes *physical, u32_t *ptent)
 {
 	u32_t *root, *pt;
 	int pde, pte;
@@ -535,8 +536,8 @@ PUBLIC int vm_contiguous(struct proc *targetproc, u32_t vir_buf, size_t bytes)
 /*===========================================================================*
  *                              vm_suspend                                *
  *===========================================================================*/
-PRIVATE void vm_suspend(struct proc *caller, struct proc *target,
-	vir_bytes linaddr, vir_bytes len, int type)
+PRIVATE void vm_suspend(struct proc *caller, const struct proc *target,
+	const vir_bytes linaddr, const vir_bytes len, const int type)
 {
 	/* This range is not OK for this process. Set parameters  
 	 * of the request and notify VM about the pending request. 
@@ -593,7 +594,7 @@ int delivermsg(struct proc *rp)
 	NOREC_RETURN(deliver, r);
 }
 
-PRIVATE char *flagstr(u32_t e, int dir)
+PRIVATE char *flagstr(u32_t e, const int dir)
 {
 	static char str[80];
 	strcpy(str, "");
@@ -610,7 +611,7 @@ PRIVATE char *flagstr(u32_t e, int dir)
 	return str;
 }
 
-PRIVATE void vm_pt_print(u32_t *pagetable, u32_t v)
+PRIVATE void vm_pt_print(u32_t *pagetable, const u32_t v)
 {
 	int pte;
 	int col = 0;
@@ -667,7 +668,7 @@ PRIVATE void vm_print(u32_t *root)
 /*===========================================================================*
  *				lin_memset				     *
  *===========================================================================*/
-int vm_phys_memset(phys_bytes ph, u8_t c, phys_bytes bytes)
+int vm_phys_memset(phys_bytes ph, const u8_t c, phys_bytes bytes)
 {
 	u32_t p;
 	NOREC_ENTER(physmemset);
@@ -857,8 +858,8 @@ int vmcheck;			/* if nonzero, can return VMSUSPEND */
 /*===========================================================================*
  *				data_copy				     *
  *===========================================================================*/
-PUBLIC int data_copy(endpoint_t from_proc, vir_bytes from_addr,
-	endpoint_t to_proc, vir_bytes to_addr,
+PUBLIC int data_copy(const endpoint_t from_proc, const vir_bytes from_addr,
+	const endpoint_t to_proc, const vir_bytes to_addr,
 	size_t bytes)
 {
   struct vir_addr src, dst;
@@ -876,8 +877,8 @@ PUBLIC int data_copy(endpoint_t from_proc, vir_bytes from_addr,
  *				data_copy_vmcheck			     *
  *===========================================================================*/
 PUBLIC int data_copy_vmcheck(struct proc * caller,
-	endpoint_t from_proc, vir_bytes from_addr,
-	endpoint_t to_proc, vir_bytes to_addr,
+	const endpoint_t from_proc, const vir_bytes from_addr,
+	const endpoint_t to_proc, const vir_bytes to_addr,
 	size_t bytes)
 {
   struct vir_addr src, dst;
@@ -894,7 +895,7 @@ PUBLIC int data_copy_vmcheck(struct proc * caller,
 /*===========================================================================*
  *				arch_pre_exec				     *
  *===========================================================================*/
-PUBLIC void arch_pre_exec(struct proc *pr, u32_t ip, u32_t sp)
+PUBLIC void arch_pre_exec(struct proc *pr, const u32_t ip, const u32_t sp)
 {
 /* wipe extra LDT entries, set program counter, and stack pointer. */
 	memset(pr->p_seg.p_ldt + EXTRA_LDT_INDEX, 0,
@@ -923,14 +924,15 @@ PUBLIC int arch_umap(struct proc *pr, vir_bytes offset, vir_bytes count,
 }
 
 /* VM reports page directory slot we're allowed to use freely. */
-void i386_freepde(int pde)
+void i386_freepde(const int pde)
 {
 	if(nfreepdes >= MAX_FREEPDES)
 		return;
 	freepdes[nfreepdes++] = pde;
 }
 
-PUBLIC int arch_phys_map(int index, phys_bytes *addr, phys_bytes *len, int *flags)
+PUBLIC int arch_phys_map(const int index, phys_bytes *addr,
+  phys_bytes *len, int *flags)
 {
 #ifdef CONFIG_APIC
 	/* map the local APIC if enabled */
@@ -947,7 +949,7 @@ PUBLIC int arch_phys_map(int index, phys_bytes *addr, phys_bytes *len, int *flag
 #endif
 }
 
-PUBLIC int arch_phys_map_reply(int index, vir_bytes addr)
+PUBLIC int arch_phys_map_reply(const int index, const vir_bytes addr)
 {
 #ifdef CONFIG_APIC
 	/* if local APIC is enabled */
@@ -958,7 +960,7 @@ PUBLIC int arch_phys_map_reply(int index, vir_bytes addr)
 	return OK;
 }
 
-PUBLIC int arch_enable_paging(struct proc * caller, message * m_ptr)
+PUBLIC int arch_enable_paging(struct proc * caller, const message * m_ptr)
 {
 	struct vm_ep_data ep_data;
 	int r;
diff --git a/kernel/arch/i386/protect.c b/kernel/arch/i386/protect.c
index a77dcbe25..7681cae61 100644
--- a/kernel/arch/i386/protect.c
+++ b/kernel/arch/i386/protect.c
@@ -48,7 +48,7 @@ PUBLIC void enable_iop(struct proc *pp)
 /*===========================================================================*
  *				seg2phys				     *
  *===========================================================================*/
-PUBLIC phys_bytes seg2phys(U16_t seg)
+PUBLIC phys_bytes seg2phys(const U16_t seg)
 {
 /* Return the base address of a segment, with seg being a 
  * register, or a 286/386 segment selector.
@@ -79,7 +79,7 @@ PRIVATE void phys2seg(u16_t *seg, vir_bytes *off, phys_bytes phys)
  *				init_dataseg				     *
  *===========================================================================*/
 PUBLIC void init_dataseg(register struct segdesc_s *segdp,
-	phys_bytes base, vir_bytes size, int privilege)
+	phys_bytes base, vir_bytes size, const int privilege)
 {
 	/* Build descriptor for a data segment. */
 	sdesc(segdp, base, size);
@@ -247,9 +247,9 @@ vir_bytes size;
  *				int_gate				     *
  *===========================================================================*/
 PUBLIC void int_gate(vec_nr, offset, dpl_type)
-unsigned vec_nr;
-vir_bytes offset;
-unsigned dpl_type;
+const unsigned vec_nr;
+const vir_bytes offset;
+const unsigned dpl_type;
 {
 /* Build descriptor for an interrupt gate. */
   register struct gatedesc_s *idp;
@@ -337,7 +337,8 @@ for (rp = BEG_PROC_ADDR; rp < END_PROC_ADDR; ++rp) {
 /*===========================================================================*
  *				printseg			     *
  *===========================================================================*/
-PUBLIC void printseg(char *banner, int iscs, struct proc *pr, u32_t selector)
+PUBLIC void printseg(char *banner, const int iscs, struct proc *pr,
+  const u32_t selector)
 {
 	u32_t base, limit, index, dpl;
 	struct segdesc_s *desc;
@@ -424,7 +425,7 @@ PUBLIC void printseg(char *banner, int iscs, struct proc *pr, u32_t selector)
 /*===========================================================================*
  *				prot_set_kern_seg_limit			     *
  *===========================================================================*/
-PUBLIC int prot_set_kern_seg_limit(vir_bytes limit)
+PUBLIC int prot_set_kern_seg_limit(const vir_bytes limit)
 {
 	struct proc *rp;
 	int orig_click;
diff --git a/kernel/arch/i386/system.c b/kernel/arch/i386/system.c
index 665d85c87..5b99df26f 100644
--- a/kernel/arch/i386/system.c
+++ b/kernel/arch/i386/system.c
@@ -36,7 +36,7 @@ PUBLIC void arch_monitor(void)
 
 PUBLIC int cpu_has_tsc;
 
-PUBLIC void arch_shutdown(int how)
+PUBLIC void arch_shutdown(const int how)
 {
 	/* Mask all interrupts, including the clock. */
 	outb( INT_CTLMASK, ~0);
@@ -66,8 +66,8 @@ PUBLIC void arch_shutdown(int how)
 		if(minix_panicing) {
 			int source, dest;
 			static char mybuffer[sizeof(params_buffer)];
-			char *lead = "echo \\n*** kernel messages:\\n";
-			int leadlen = strlen(lead);
+			const char *lead = "echo \\n*** kernel messages:\\n";
+			const int leadlen = strlen(lead);
 			strcpy(mybuffer, lead);
 
 #define DECSOURCE source = (source - 1 + _KMESS_BUF_SIZE) % _KMESS_BUF_SIZE
@@ -79,7 +79,7 @@ PUBLIC void arch_shutdown(int how)
 			DECSOURCE; 
 
 			while(dest >= leadlen) {
-				char c = kmess.km_buf[source];
+				const char c = kmess.km_buf[source];
 				if(c == '\n') {
 					mybuffer[dest--] = 'n';
 					mybuffer[dest] = '\\';
@@ -110,7 +110,7 @@ PUBLIC void arch_shutdown(int how)
 /* address of a.out headers, set in mpx386.s */
 phys_bytes aout;
 
-PUBLIC void arch_get_aout_headers(int i, struct exec *h)
+PUBLIC void arch_get_aout_headers(const int i, struct exec *h)
 {
 	/* The bootstrap loader created an array of the a.out headers at
 	 * absolute address 'aout'. Get one element to h.
@@ -118,7 +118,8 @@ PUBLIC void arch_get_aout_headers(int i, struct exec *h)
 	phys_copy(aout + i * A_MINHDR, vir2phys(h), (phys_bytes) A_MINHDR);
 }
 
-PRIVATE void tss_init(struct tss_s * tss, void * kernel_stack, unsigned cpu)
+PRIVATE void tss_init(struct tss_s * tss, void * kernel_stack,
+ const unsigned cpu)
 {
 	/*
 	 * make space for process pointer and cpu id and point to the first
@@ -275,7 +276,7 @@ PRIVATE void ser_dump_segs(void)
 	}
 }
 
-PRIVATE void ser_debug(int c)
+PRIVATE void ser_debug(const int c)
 {
 	serial_debug_active = 1;
 
@@ -312,7 +313,7 @@ PRIVATE void ser_debug(int c)
 	serial_debug_active = 0;
 }
 
-PRIVATE void printslot(struct proc *pp, int level)
+PRIVATE void printslot(struct proc *pp, const int level)
 {
 	struct proc *depproc = NULL;
 	endpoint_t dep;
@@ -376,7 +377,7 @@ PUBLIC void ser_dump_proc()
 
 #if SPROFILE
 
-PUBLIC int arch_init_profile_clock(u32_t freq)
+PUBLIC int arch_init_profile_clock(const u32_t freq)
 {
   int r;
   /* Set CMOS timer frequency. */
@@ -415,7 +416,7 @@ PUBLIC void arch_ack_profile_clock(void)
 
 #define COLOR_BASE	0xB8000L
 
-PRIVATE void cons_setc(int pos, int c)
+PRIVATE void cons_setc(const int pos, const int c)
 {
 	char ch;
 
diff --git a/kernel/arch/i386/watchdog.c b/kernel/arch/i386/watchdog.c
index 8cada4f63..41a876c20 100644
--- a/kernel/arch/i386/watchdog.c
+++ b/kernel/arch/i386/watchdog.c
@@ -44,7 +44,7 @@ PRIVATE void intel_arch_watchdog_init(int cpu)
 	lapic_write(LAPIC_LVTPCR, APIC_ICR_DM_NMI);
 }
 
-PRIVATE void intel_arch_watchdog_reinit(int cpu)
+PRIVATE void intel_arch_watchdog_reinit(const int cpu)
 {
 	lapic_write(LAPIC_LVTPCR, APIC_ICR_DM_NMI);
 	ia32_msr_write(MSR_PERFMON_CRT0, 0, -watchdog->resetval);
@@ -86,7 +86,7 @@ int arch_watchdog_init(void)
 	return 0;
 }
 
-void arch_watchdog_lockup(struct nmi_frame * frame)
+void arch_watchdog_lockup(const struct nmi_frame * frame)
 {
 	printf("KERNEL LOCK UP\n"
 			"eax    0x%08x\n"
diff --git a/kernel/clock.c b/kernel/clock.c
index 0e453ed2e..d42560180 100644
--- a/kernel/clock.c
+++ b/kernel/clock.c
@@ -185,7 +185,7 @@ PUBLIC int ap_timer_int_handler(void)
 	 * user's system time.
 	 */
 
-	unsigned ticks = 1;
+	const unsigned ticks = 1;
 	struct proc * p, * billp;
 
 #ifdef CONFIG_WATCHDOG
diff --git a/kernel/debug.c b/kernel/debug.c
index 89d430fc8..9fc79255f 100644
--- a/kernel/debug.c
+++ b/kernel/debug.c
@@ -38,7 +38,8 @@ runqueues_ok(void)
 	return 0;
     }
     for(xp = rdy_head[q]; xp != NIL_PROC; xp = xp->p_nextready) {
-	vir_bytes vxp = (vir_bytes) xp, dxp;
+	const vir_bytes vxp = (vir_bytes) xp;
+	vir_bytes dxp;
 	if(vxp < (vir_bytes) BEG_PROC_ADDR || vxp >= (vir_bytes) END_PROC_ADDR) {
   		printf("xp out of range\n");
 		return 0;
@@ -108,7 +109,7 @@ runqueues_ok(void)
 }
 
 PUBLIC char *
-rtsflagstr(int flags)
+rtsflagstr(const int flags)
 {
 	static char str[100];
 	str[0] = '\0';
@@ -135,7 +136,7 @@ rtsflagstr(int flags)
 }
 
 PUBLIC char *
-miscflagstr(int flags)
+miscflagstr(const int flags)
 {
 	static char str[100];
 	str[0] = '\0';
diff --git a/kernel/interrupt.c b/kernel/interrupt.c
index 123a06fe7..6482d8e32 100644
--- a/kernel/interrupt.c
+++ b/kernel/interrupt.c
@@ -27,7 +27,8 @@ PUBLIC irq_hook_t* irq_handlers[NR_IRQ_VECTORS] = {0};
  *				put_irq_handler				     *
  *===========================================================================*/
 /* Register an interrupt handler.  */
-PUBLIC void put_irq_handler( irq_hook_t* hook, int irq, irq_handler_t handler)
+PUBLIC void put_irq_handler( irq_hook_t* hook, int irq,
+  const irq_handler_t handler)
 {
   int id;
   irq_hook_t **line;
@@ -72,9 +73,9 @@ PUBLIC void put_irq_handler( irq_hook_t* hook, int irq, irq_handler_t handler)
  *				rm_irq_handler				     *
  *===========================================================================*/
 /* Unregister an interrupt handler.  */
-PUBLIC void rm_irq_handler( irq_hook_t* hook ) {
-  int irq = hook->irq; 
-  int id = hook->id;
+PUBLIC void rm_irq_handler( const irq_hook_t* hook ) {
+  const int irq = hook->irq; 
+  const int id = hook->id;
   irq_hook_t **line;
 
   if( irq < 0 || irq >= NR_IRQ_VECTORS ) 
@@ -155,8 +156,7 @@ PUBLIC void irq_handle(int irq)
 }
 
 /* Enable/Disable a interrupt line.  */
-PUBLIC void enable_irq(hook)
-irq_hook_t* hook;
+PUBLIC void enable_irq(const irq_hook_t *hook)
 {
   if((irq_actids[hook->irq] &= ~hook->id) == 0) {
     hw_intr_unmask(hook->irq);
@@ -164,8 +164,7 @@ irq_hook_t* hook;
 }
 
 /* Return true if the interrupt was enabled before call.  */
-PUBLIC int disable_irq(hook)
-irq_hook_t* hook;
+PUBLIC int disable_irq(const irq_hook_t *hook)
 {
   if(irq_actids[hook->irq] & hook->id)  /* already disabled */
     return 0;
diff --git a/kernel/main.c b/kernel/main.c
index daf0989c2..84bd346c6 100644
--- a/kernel/main.c
+++ b/kernel/main.c
@@ -283,8 +283,7 @@ PRIVATE void announce(void)
 /*===========================================================================*
  *				prepare_shutdown			     *
  *===========================================================================*/
-PUBLIC void prepare_shutdown(how)
-int how;
+PUBLIC void prepare_shutdown(const int how)
 {
 /* This function prepares to shutdown MINIX. */
   static timer_t shutdown_timer;
@@ -301,8 +300,7 @@ int how;
 /*===========================================================================*
  *				shutdown 				     *
  *===========================================================================*/
-PUBLIC void minix_shutdown(tp)
-timer_t *tp;
+PUBLIC void minix_shutdown(timer_t *tp)
 {
 /* This function is called from prepare_shutdown or stop_sequence to bring 
  * down MINIX. How to shutdown is in the argument: RBT_HALT (return to the
diff --git a/kernel/proc.c b/kernel/proc.c
index 7062c5899..208f8268a 100644
--- a/kernel/proc.c
+++ b/kernel/proc.c
@@ -279,7 +279,7 @@ long bit_map;			/* notification event set or flags */
  * The trap is caught and sys_call() is called to send or receive a message
  * (or both). The caller is always given by 'proc_ptr'.
  */
-  register struct proc *caller_ptr = proc_ptr;	/* get pointer to caller */
+  struct proc *const caller_ptr = proc_ptr;	/* get pointer to caller */
   int result;					/* the system call's result */
   int src_dst_p;				/* Process slot number */
   size_t msg_size;
@@ -537,7 +537,7 @@ PRIVATE int mini_send(caller_ptr, dst_e, m_ptr, flags)
 register struct proc *caller_ptr;	/* who is trying to send a message? */
 int dst_e;				/* to whom is message being sent? */
 message *m_ptr;				/* pointer to message buffer */
-int flags;
+const int flags;
 {
 /* Send a message from 'caller_ptr' to 'dst'. If 'dst' is blocked waiting
  * for this message, copy the message to it and unblock 'dst'. If 'dst' is
@@ -609,7 +609,7 @@ PRIVATE int mini_receive(caller_ptr, src_e, m_ptr, flags)
 register struct proc *caller_ptr;	/* process trying to get message */
 int src_e;				/* which message source is wanted */
 message *m_ptr;				/* pointer to message buffer */
-int flags;
+const int flags;
 {
 /* A process or task wants to get a message.  If a message is already queued,
  * acquire it and deblock the sender.  If no message from the desired source
@@ -742,9 +742,10 @@ int flags;
 /*===========================================================================*
  *				mini_notify				     * 
  *===========================================================================*/
-PUBLIC int mini_notify(caller_ptr, dst_e)
-register struct proc *caller_ptr;	/* sender of the notification */
-endpoint_t dst_e;			/* which process to notify */
+PUBLIC int mini_notify(
+  const struct proc *caller_ptr,	/* sender of the notification */
+  endpoint_t dst_e			/* which process to notify */
+)
 {
   register struct proc *dst_ptr;
   int src_id;				/* source id for late delivery */
@@ -821,7 +822,7 @@ PRIVATE int mini_senda(struct proc *caller_ptr, asynmsg_t *table, size_t size)
 	struct proc *dst_ptr;
 	struct priv *privp;
 	asynmsg_t tabent;
-	vir_bytes table_v = (vir_bytes) table;
+	const vir_bytes table_v = (vir_bytes) table;
 	vir_bytes linaddr;
 
 	privp= priv(caller_ptr);
@@ -1133,8 +1134,9 @@ PRIVATE int try_one(struct proc *src_ptr, struct proc *dst_ptr, int *postponed)
 /*===========================================================================*
  *				enqueue					     * 
  *===========================================================================*/
-PUBLIC void enqueue(rp)
-register struct proc *rp;	/* this process is now runnable */
+PUBLIC void enqueue(
+  register struct proc *rp	/* this process is now runnable */
+)
 {
 /* Add 'rp' to one of the queues of runnable processes.  This function is 
  * responsible for inserting a process into one of the scheduling queues. 
@@ -1196,7 +1198,7 @@ register struct proc *rp;	/* this process is now runnable */
  */
 PRIVATE void enqueue_head(struct proc *rp)
 {
-  int q = rp->p_priority;	 		/* scheduling queue to use */
+  const int q = rp->p_priority;	 		/* scheduling queue to use */
 
   assert(proc_ptr_ok(rp));
   assert(proc_is_runnable(rp));
@@ -1229,8 +1231,8 @@ PRIVATE void enqueue_head(struct proc *rp)
 /*===========================================================================*
  *				dequeue					     * 
  *===========================================================================*/
-PUBLIC void dequeue(rp)
-register struct proc *rp;	/* this process is no longer runnable */
+PUBLIC void dequeue(const struct proc *rp)
+/* this process is no longer runnable */
 {
 /* A process must be removed from the scheduling queues, for example, because
  * it has blocked.  If the currently active process is removed, a new process
@@ -1284,7 +1286,7 @@ int *front;					/* return: front or back */
  * process must be added to one of the scheduling queues to decide where to
  * insert it.  As a side-effect the process' priority may be updated.  
  */
-  int time_left = (rp->p_ticks_left > 0);	/* quantum fully consumed */
+  const int time_left = (rp->p_ticks_left > 0);	/* quantum fully consumed? */
 
   /* Check whether the process has time left. Otherwise give a new quantum 
    * and lower the process' priority, unless the process already is in the 
@@ -1340,8 +1342,9 @@ PRIVATE struct proc * pick_proc(void)
  *				balance_queues				     *
  *===========================================================================*/
 #define Q_BALANCE_TICKS	 100
-PUBLIC void balance_queues(tp)
-timer_t *tp;					/* watchdog timer pointer */
+PUBLIC void balance_queues(
+  timer_t *tp				/* watchdog timer pointer */
+)
 {
 /* Check entire process table and give all process a higher priority. This
  * effectively means giving a new quantum. If a process already is at its 
@@ -1398,13 +1401,14 @@ PUBLIC struct proc *endpoint_lookup(endpoint_t e)
  *===========================================================================*/
 #if DEBUG_ENABLE_IPC_WARNINGS
 PUBLIC int isokendpt_f(file, line, e, p, fatalflag)
-char *file;
+const char *file;
 int line;
 #else
 PUBLIC int isokendpt_f(e, p, fatalflag)
 #endif
 endpoint_t e;
-int *p, fatalflag;
+int *p;
+const int fatalflag;
 {
 	int ok = 0;
 	/* Convert an endpoint number into a process number.
diff --git a/kernel/proc.h b/kernel/proc.h
index 0d8d7271d..df7262bb7 100644
--- a/kernel/proc.h
+++ b/kernel/proc.h
@@ -176,7 +176,7 @@ struct proc {
 /* Set flag and dequeue if the process was runnable. */
 #define RTS_SET(rp, f)							\
 	do {								\
-		int rts = (rp)->p_rts_flags;				\
+		const int rts = (rp)->p_rts_flags;			\
 		(rp)->p_rts_flags |= (f);				\
 		if(rts_f_is_runnable(rts) && !proc_is_runnable(rp)) {	\
 			dequeue(rp);					\
diff --git a/kernel/profile.c b/kernel/profile.c
index 1a387e54f..84ec551ba 100644
--- a/kernel/profile.c
+++ b/kernel/profile.c
@@ -69,8 +69,7 @@ PUBLIC void stop_profile_clock()
 /*===========================================================================*
  *			profile_clock_handler                           *
  *===========================================================================*/
-PRIVATE int profile_clock_handler(hook)
-irq_hook_t *hook;
+PRIVATE int profile_clock_handler(irq_hook_t *hook)
 {
 /* This executes on every tick of the CMOS timer. */
 
diff --git a/kernel/proto.h b/kernel/proto.h
index 451bb9d71..858f5bc6f 100644
--- a/kernel/proto.h
+++ b/kernel/proto.h
@@ -38,15 +38,15 @@ _PROTOTYPE( void minix_shutdown, (struct timer *tp)			);
 /* proc.c */
 _PROTOTYPE( int do_ipc, (int call_nr, int src_dst, 
 					message *m_ptr, long bit_map)	);
-_PROTOTYPE( int mini_notify, (struct proc *src, endpoint_t dst)		);
+_PROTOTYPE( int mini_notify, (const struct proc *src, endpoint_t dst)	);
 _PROTOTYPE( void enqueue, (struct proc *rp)				);
-_PROTOTYPE( void dequeue, (struct proc *rp)				);
+_PROTOTYPE( void dequeue, (const struct proc *rp)			);
 _PROTOTYPE( void balance_queues, (struct timer *tp)			);
 _PROTOTYPE( struct proc * schedcheck, (void)				);
 _PROTOTYPE( struct proc * arch_finish_schedcheck, (void)		);
 _PROTOTYPE( struct proc *endpoint_lookup, (endpoint_t ep)		);
 #if DEBUG_ENABLE_IPC_WARNINGS
-_PROTOTYPE( int isokendpt_f, (char *file, int line, endpoint_t e, int *p, int f));
+_PROTOTYPE( int isokendpt_f, (const char *file, int line, endpoint_t e, int *p, int f));
 #define isokendpt_d(e, p, f) isokendpt_f(__FILE__, __LINE__, (e), (p), (f))
 #else
 _PROTOTYPE( int isokendpt_f, (endpoint_t e, int *p, int f)		);
@@ -59,8 +59,8 @@ _PROTOTYPE( void cstart, (U16_t cs, U16_t ds, U16_t mds,
 
 /* system.c */
 _PROTOTYPE( int get_priv, (register struct proc *rc, int proc_type)	);
-_PROTOTYPE( void set_sendto_bit, (struct proc *rc, int id)		);
-_PROTOTYPE( void unset_sendto_bit, (struct proc *rc, int id)		);
+_PROTOTYPE( void set_sendto_bit, (const struct proc *rc, int id)	);
+_PROTOTYPE( void unset_sendto_bit, (const struct proc *rc, int id)	);
 _PROTOTYPE( void send_sig, (int proc_nr, int sig_nr)			);
 _PROTOTYPE( void cause_sig, (proc_nr_t proc_nr, int sig_nr)			);
 _PROTOTYPE( void sig_delay_done, (struct proc *rp)			);
@@ -83,9 +83,9 @@ _PROTOTYPE( void vtimer_check, (struct proc *rp)			);
 /* interrupt.c */
 _PROTOTYPE( void put_irq_handler, (irq_hook_t *hook, int irq,
 						 irq_handler_t handler)  );
-_PROTOTYPE( void rm_irq_handler, (irq_hook_t *hook)                      );
-_PROTOTYPE( void enable_irq, (irq_hook_t *hook)                        	);
-_PROTOTYPE( int disable_irq, (irq_hook_t *hook)                        );
+_PROTOTYPE( void rm_irq_handler, (const irq_hook_t *hook)		);
+_PROTOTYPE( void enable_irq, (const irq_hook_t *hook)			);
+_PROTOTYPE( int disable_irq, (const irq_hook_t *hook)			);
 
 /* debug.c */
 _PROTOTYPE( int runqueues_ok, (void) );
@@ -136,7 +136,7 @@ _PROTOTYPE( phys_bytes umap_local, (register struct proc *rp, int seg,
 	vir_bytes vir_addr, vir_bytes bytes));
 _PROTOTYPE( void cp_mess, (int src,phys_clicks src_clicks,
         vir_bytes src_offset, phys_clicks dst_clicks, vir_bytes dst_offset));
-_PROTOTYPE( phys_bytes umap_remote, (struct proc* rp, int seg,
+_PROTOTYPE( phys_bytes umap_remote, (const struct proc* rp, int seg,
         vir_bytes vir_addr, vir_bytes bytes)				);
 _PROTOTYPE( phys_bytes umap_virtual, (struct proc* rp,
 			int seg, vir_bytes vir_addr, vir_bytes bytes)	);
@@ -167,13 +167,13 @@ _PROTOTYPE( int arch_umap, (struct proc *pr, vir_bytes, vir_bytes,
 _PROTOTYPE( int arch_do_vmctl, (message *m_ptr, struct proc *p)); 
 _PROTOTYPE( int vm_contiguous, (struct proc *targetproc, u32_t vir_buf, size_t count));
 _PROTOTYPE( void proc_stacktrace, (struct proc *proc)	         );
-_PROTOTYPE( int vm_lookup, (struct proc *proc, vir_bytes virtual, vir_bytes *result, u32_t *ptent));
+_PROTOTYPE( int vm_lookup, (const struct proc *proc, vir_bytes virtual, vir_bytes *result, u32_t *ptent));
 _PROTOTYPE( int delivermsg, (struct proc *target));
 _PROTOTYPE( void arch_do_syscall, (struct proc *proc)			);
 _PROTOTYPE( int arch_phys_map, (int index, phys_bytes *addr,
 	phys_bytes *len, int *flags));
 _PROTOTYPE( int arch_phys_map_reply, (int index, vir_bytes addr));
-_PROTOTYPE( int arch_enable_paging, (struct proc * caller, message * m_ptr));
+_PROTOTYPE( int arch_enable_paging, (struct proc * caller, const message * m_ptr));
 
 _PROTOTYPE( int copy_msg_from_user, (struct proc * p, message * user_mbuf,
 							message * dst));
diff --git a/kernel/start.c b/kernel/start.c
index 8edffc28f..75e875ee6 100644
--- a/kernel/start.c
+++ b/kernel/start.c
@@ -11,7 +11,7 @@
 #include "watchdog.h"
 #endif
 
-FORWARD _PROTOTYPE( char *get_value, (_CONST char *params, _CONST char *key));
+FORWARD _PROTOTYPE( char *get_value, (const char *params, const char *key));
 /*===========================================================================*
  *				cstart					     *
  *===========================================================================*/
@@ -112,13 +112,13 @@ U16_t parmoff, parmsize;	/* boot parameters offset and length */
  *===========================================================================*/
 
 PRIVATE char *get_value(params, name)
-_CONST char *params;				/* boot monitor parameters */
-_CONST char *name;				/* key to look up */
+  const char *params;				/* boot monitor parameters */
+  const char *name;				/* key to look up */
 {
 /* Get environment value - kernel version of getenv to avoid setting up the
  * usual environment array.
  */
-  register _CONST char *namep;
+  register const char *namep;
   register char *envp;
 
   for (envp = (char *) params; *envp != 0;) {
diff --git a/kernel/system.c b/kernel/system.c
index 28ab09cd1..49e2f08f0 100644
--- a/kernel/system.c
+++ b/kernel/system.c
@@ -281,7 +281,7 @@ int priv_id;				/* privilege id */
 /*===========================================================================*
  *				set_sendto_bit				     *
  *===========================================================================*/
-PUBLIC void set_sendto_bit(struct proc *rp, int id)
+PUBLIC void set_sendto_bit(const struct proc *rp, int id)
 {
 /* Allow a process to send messages to the process(es) associated with the
  * system privilege structure with the given ID. 
@@ -309,7 +309,7 @@ PUBLIC void set_sendto_bit(struct proc *rp, int id)
 /*===========================================================================*
  *				unset_sendto_bit			     *
  *===========================================================================*/
-PUBLIC void unset_sendto_bit(struct proc *rp, int id)
+PUBLIC void unset_sendto_bit(const struct proc *rp, int id)
 {
 /* Prevent a process from sending to another process. Retain the send mask
  * symmetry by also unsetting the bit for the other direction.
diff --git a/kernel/watchdog.h b/kernel/watchdog.h
index 132fed9ac..9dd36ddc0 100644
--- a/kernel/watchdog.h
+++ b/kernel/watchdog.h
@@ -26,7 +26,7 @@ extern struct arch_watchdog *watchdog;
 /* let the arch code do whatever it needs to setup the watchdog */
 int arch_watchdog_init(void);
 /* if the watchdog detects lockup, let the arch code to handle it */
-void arch_watchdog_lockup(struct nmi_frame * frame);
+void arch_watchdog_lockup(const struct nmi_frame * frame);
 
 /* generic NMI handler. Takes one agument which points to where the arch
  * specific low level handler dumped CPU information and can be inspected by the
diff --git a/lib/libc/ansi/misc.c b/lib/libc/ansi/misc.c
index 9bb320dee..42333e055 100644
--- a/lib/libc/ansi/misc.c
+++ b/lib/libc/ansi/misc.c
@@ -188,7 +188,7 @@ parseRule(register char *buf, register const char *p)
 }
 
 static int
-last_sunday(register int day, register struct tm *timep)
+last_sunday(register int day, const register struct tm *timep)
 {
 	int first = FIRSTSUNDAY(timep);
 
@@ -198,7 +198,7 @@ last_sunday(register int day, register struct tm *timep)
 }
 
 static int
-date_of(register struct dsttype *dst, struct tm *timep)
+date_of(const register struct dsttype *dst, const struct tm *timep)
 {
 	int leap = LEAPYEAR(YEAR0 + timep->tm_year);
 	int firstday, tmpday;