diff --git a/boot/boot.c b/boot/boot.c
index 5e613973b..c72838fc1 100644
--- a/boot/boot.c
+++ b/boot/boot.c
@@ -1494,7 +1494,7 @@ static void ls(char *dir)
 	}
 	(void) r_readdir(name);	/* Skip ".." too. */
 
-	while ((ino= r_readdir(name)) != 0) printf("%s/%s\n", dir, name);
+	while (r_readdir(name) != 0) printf("%s/%s\n", dir, name);
 }
 
 static u32_t milli_time(void)
diff --git a/commands/ash/error.c b/commands/ash/error.c
index a24807e44..a56d0f228 100644
--- a/commands/ash/error.c
+++ b/commands/ash/error.c
@@ -49,13 +49,10 @@ __FBSDID("$FreeBSD: src/bin/sh/error.c,v 1.25 2004/04/06 20:06:51 markm Exp $");
 #include "options.h"
 #include "output.h"
 #include "error.h"
-#include "nodes.h" /* show.h needs nodes.h */
-#include "show.h"
 #include "trap.h"
 #include <signal.h>
 #include <stdlib.h>
 #include <unistd.h>
-#include <errno.h>
 #include <sys/types.h>
 
 
diff --git a/drivers/audio/es1370/es1370.c b/drivers/audio/es1370/es1370.c
index 3832f6662..c690dee17 100644
--- a/drivers/audio/es1370/es1370.c
+++ b/drivers/audio/es1370/es1370.c
@@ -620,7 +620,8 @@ PRIVATE int get_samples_in_buf (u32_t *samples_in_buf, int *len, int chan) {
 		default: return EINVAL;
 	}
 
-	samp_ct = pci_inw(reg(samp_ct_reg));
+	/* TODO: is this inw useful? */
+	(void) pci_inw(reg(samp_ct_reg));
 	curr_samp_ct = pci_inw(reg(curr_samp_ct_reg));
 
 	*samples_in_buf = (u32_t) (sub_dev[chan].BufLength * 8192) + 
diff --git a/drivers/audio/es1371/es1371.c b/drivers/audio/es1371/es1371.c
index a65a6d1c4..9ac2fc121 100644
--- a/drivers/audio/es1371/es1371.c
+++ b/drivers/audio/es1371/es1371.c
@@ -622,7 +622,8 @@ PRIVATE int get_samples_in_buf (u32_t *samples_in_buf, int *len, int chan) {
 		default: return EINVAL;
 	}
 
-	samp_ct = pci_inw(reg(samp_ct_reg));
+	/* TODO: is this statement useful? */
+	(void) pci_inw(reg(samp_ct_reg));
 	curr_samp_ct = pci_inw(reg(curr_samp_ct_reg));
 
 	*samples_in_buf = (u32_t) (sub_dev[chan].BufLength * 8192) + 
diff --git a/drivers/dec21140A/dec21140A.c b/drivers/dec21140A/dec21140A.c
index a9f3b60f5..1ac73f2e3 100644
--- a/drivers/dec21140A/dec21140A.c
+++ b/drivers/dec21140A/dec21140A.c
@@ -156,7 +156,6 @@ PRIVATE void sef_local_startup()
 PRIVATE int sef_cb_init_fresh(int type, sef_init_info_t *UNUSED(info))
 {
 /* Initialize the DEC 21140A driver. */
-  int r;
   int fkeys, sfkeys;
 
   (progname=strrchr(env_argv[0],'/')) ? progname++ : (progname=env_argv[0]);
diff --git a/drivers/dp8390/dp8390.c b/drivers/dp8390/dp8390.c
index 9c152ce80..ad15fe054 100644
--- a/drivers/dp8390/dp8390.c
+++ b/drivers/dp8390/dp8390.c
@@ -318,7 +318,7 @@ PRIVATE void sef_local_startup()
 PRIVATE int sef_cb_init_fresh(int type, sef_init_info_t *UNUSED(info))
 {
 /* Initialize the dp8390 driver. */
-	int i, r;
+	int i;
 	dpeth_t *dep;
 	long v;
 
@@ -879,8 +879,7 @@ dpeth_t *dep;
 /*===========================================================================*
  *				do_getstat				     *
  *===========================================================================*/
-static void do_getstat(mp)
-message *mp;
+static void do_getstat(message *mp)
 {
 	int port, r;
 	dpeth_t *dep;
diff --git a/drivers/dpeth/8390.c b/drivers/dpeth/8390.c
index 51a200466..5240844ba 100644
--- a/drivers/dpeth/8390.c
+++ b/drivers/dpeth/8390.c
@@ -89,12 +89,12 @@ static void mem_getblock(dpeth_t *dep, u16_t offset, int size, void *dst)
 */
 static void mem_nic2user(dpeth_t * dep, int pageno, int pktsize)
 {
+  panic("mem_nic2user: not converted to safecopies");
+#if 0
   phys_bytes offset;
   iovec_dat_s_t *iovp = &dep->de_read_iovec;
   int bytes, ix = 0;
 
-  panic("mem_nic2user: not converted to safecopies");
-#if 0
 
   /* Computes shared memory address (skipping receive header) */
   offset = pageno * DP_PAGESIZE + sizeof(dp_rcvhdr_t);
diff --git a/drivers/dpeth/dp.c b/drivers/dpeth/dp.c
index 927848ac0..e536f9f5a 100644
--- a/drivers/dpeth/dp.c
+++ b/drivers/dpeth/dp.c
@@ -283,7 +283,6 @@ static void do_init(const message * mp)
   dpeth_t *dep;
   dp_conf_t *dcp;
   message reply_mess;
-  const char *portname;
 
   port = mp->DL_PORT;
   if (port >= 0 && port < DE_PORT_NR) {
@@ -292,7 +291,6 @@ static void do_init(const message * mp)
 	dcp = &dp_conf[port];
 	strcpy(dep->de_name, DevName);
 	dep->de_name[4] = '0' + port;
-	portname = dep->de_name;
 
 	if (dep->de_mode == DEM_DISABLED) {
 
@@ -345,7 +343,6 @@ static void do_init(const message * mp)
 
   } else {			/* Port number is out of range */
 	port = ENXIO;
-	portname = "(illegal dpeth port)";
   }
 
   reply_mess.m_type = DL_CONF_REPLY;
@@ -667,7 +664,7 @@ PRIVATE void sef_local_startup()
 PRIVATE int sef_cb_init_fresh(int type, sef_init_info_t *UNUSED(info))
 {
 /* Initialize the dpeth driver. */
-  int r, rc, fkeys, sfkeys;
+  int fkeys, sfkeys;
 
   (progname=strrchr(env_argv[0],'/')) ? progname++ : (progname=env_argv[0]);
 
diff --git a/drivers/dpeth/dp.h b/drivers/dpeth/dp.h
index a0ec2d765..836346b9d 100644
--- a/drivers/dpeth/dp.h
+++ b/drivers/dpeth/dp.h
@@ -279,7 +279,7 @@ int wdeth_probe(dpeth_t * dep);
 #endif
 
 #define lock()	 (++dep->de_int_pending,sys_irqdisable(&dep->de_hook))
-#define unlock() do{int i=(--dep->de_int_pending)?0:sys_irqenable(&dep->de_hook);}while(0)
+#define unlock() do{int i=(--dep->de_int_pending)?0:sys_irqenable(&dep->de_hook);(void) i;}while(0)
 #define milli_delay(t) tickdelay(1)
 
 /** dp.h **/
diff --git a/drivers/e1000/e1000.c b/drivers/e1000/e1000.c
index e328ae757..214ef69fd 100644
--- a/drivers/e1000/e1000.c
+++ b/drivers/e1000/e1000.c
@@ -248,7 +248,7 @@ PRIVATE int e1000_probe(e1000_t *e)
     int i, r, devind;
     u16_t vid, did;
     u32_t status[2];
-    u32_t gfpreg, sector_base_addr, sector_end_addr;
+    u32_t gfpreg, sector_base_addr;
     char *dname;
 
     E1000_DEBUG(3, ("%s: probe()\n", e->name));
@@ -338,12 +338,9 @@ PRIVATE int e1000_probe(e1000_t *e)
 
 	gfpreg = E1000_READ_FLASH_REG(e, ICH_FLASH_GFPREG);
         /*
-         * sector_X_addr is a "sector"-aligned address (4096 bytes)
-         * Add 1 to sector_end_addr since this sector is included in
-         * the overall size.
+         * sector_base_addr is a "sector"-aligned address (4096 bytes)
          */
         sector_base_addr = gfpreg & FLASH_GFPREG_BASE_MASK;
-        sector_end_addr = ((gfpreg >> 16) & FLASH_GFPREG_BASE_MASK) + 1;
 
         /* flash_base_addr is byte-aligned */
         e->flash_base_addr = sector_base_addr << FLASH_SECTOR_ADDR_SHIFT;
diff --git a/drivers/filter/driver.c b/drivers/filter/driver.c
index 4738ef99a..77582b3c3 100644
--- a/drivers/filter/driver.c
+++ b/drivers/filter/driver.c
@@ -419,8 +419,7 @@ static void restart_driver(int which, int tell_rs)
 	 */
 	message msg;
 	int ipc_status;
-	endpoint_t endpt;
-	int r, w = 0;
+	int r;
 
 	if (tell_rs) {
 		/* Tell RS to refresh or restart the driver */
diff --git a/drivers/fxp/fxp.c b/drivers/fxp/fxp.c
index 09aa88e6f..e38063f1f 100644
--- a/drivers/fxp/fxp.c
+++ b/drivers/fxp/fxp.c
@@ -722,8 +722,7 @@ static int fxp_probe(fxp_t *fp)
 /*===========================================================================*
  *				fxp_conf_hw				     *
  *===========================================================================*/
-static void fxp_conf_hw(fp)
-fxp_t *fp;
+static void fxp_conf_hw(fxp_t *fp)
 {
 	int i;
 	int mwi, ext_stat1, ext_stat2, lim_fifo, i82503, fc;
diff --git a/drivers/lance/lance.c b/drivers/lance/lance.c
index 10eb68f07..10ef1e4dc 100644
--- a/drivers/lance/lance.c
+++ b/drivers/lance/lance.c
@@ -1472,7 +1472,6 @@ ether_card_t *ec;
    int devind, just_one, i, r;
 
    u16_t vid, did;
-   char *dname;
 
    if ((ec->ec_pcibus | ec->ec_pcidev | ec->ec_pcifunc) != 0)
    {
@@ -1528,10 +1527,6 @@ ether_card_t *ec;
          return 0;
    }
 
-   dname= pci_dev_name(vid, did);
-   if (!dname)
-      dname= "unknown device";
-
    pci_reserve(devind);
 
    getAddressing(devind, ec);
diff --git a/drivers/log/log.c b/drivers/log/log.c
index 79dddd303..a2e72ec42 100644
--- a/drivers/log/log.c
+++ b/drivers/log/log.c
@@ -299,7 +299,6 @@ unsigned nr_req;		/* length of request vector */
 /* Read or write one the driver's minor devices. */
   unsigned count;
   vir_bytes user_vir;
-  struct device *dv;
   int accumulated_read = 0;
   struct logdevice *log;
   size_t vir_offset = 0;
@@ -308,7 +307,6 @@ unsigned nr_req;		/* length of request vector */
   	return EIO;
 
   /* Get minor device number and check for /dev/null. */
-  dv = &log_geom[log_device];
   log = &logdevices[log_device];
 
   while (nr_req > 0) {
diff --git a/drivers/orinoco/orinoco.c b/drivers/orinoco/orinoco.c
index 61c8e5310..eb58bfb4a 100644
--- a/drivers/orinoco/orinoco.c
+++ b/drivers/orinoco/orinoco.c
@@ -1507,18 +1507,15 @@ suspend_write:
  * Write data which is denoted by the message to the card and send it.       *
  *****************************************************************************/
 static void or_writev_s (message * mp, int from_int) {
-	int port, or_client, count, size, err, data_len, data_off, tx_head;
+	int port, or_client, count, size, err, data_len, data_off;
 	int o, j, n, i, s, p, cps ;
 	struct ethhdr *eh;
 	t_or *orp;
-	clock_t timebefore, t0;	
-	phys_bytes phys_user;
 	hermes_t *hw;
 	struct hermes_tx_descriptor desc;
 	int iov_offset = 0;
 	struct header_struct hdr;
 	iovec_s_t *iovp;
-	phys_bytes phys_databuf;
 	u16_t txfid;
 
 	/* We need space for the max packet size itself, plus an ethernet
diff --git a/drivers/pci/main.c b/drivers/pci/main.c
index 64812764d..11f53c055 100644
--- a/drivers/pci/main.c
+++ b/drivers/pci/main.c
@@ -150,8 +150,7 @@ message *mp;
 	}
 }
 
-PRIVATE void do_next_dev(mp)
-message *mp;
+PRIVATE void do_next_dev(message *mp)
 {
 	int r, devind;
 	u16_t vid, did;
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 6362ce4f9..759ec5e49 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -295,7 +295,7 @@ PUBLIC int pci_first_dev_a(
   u16_t *didp
 )
 {
-	int i, devind;
+	int devind;
 
 	for (devind= 0; devind < nr_pcidev; devind++)
 	{
@@ -2279,12 +2279,8 @@ PRIVATE void pcibr_cb_wsts(int busind, u16_t value)
 /*===========================================================================*
  *				pcibr_via_rsts				     *
  *===========================================================================*/
-PRIVATE u16_t pcibr_via_rsts(busind)
-int busind;
+PRIVATE u16_t pcibr_via_rsts(int busind)
 {
-	int devind;
-	devind= pcibus[busind].pb_devind;
-
 	return 0;
 }
 
diff --git a/drivers/rtl8139/rtl8139.c b/drivers/rtl8139/rtl8139.c
index 3be5331e5..9da970e26 100644
--- a/drivers/rtl8139/rtl8139.c
+++ b/drivers/rtl8139/rtl8139.c
@@ -2407,8 +2407,7 @@ static void do_hard_int(void)
 /*===========================================================================*
  *				rl_handler				     *
  *===========================================================================*/
-static int rl_handler(rep)
-re_t *rep;
+static int rl_handler(re_t *rep)
 {
 	int i, port, tx_head, tx_tail, link_up;
 	u16_t isr, tsad;
diff --git a/drivers/rtl8169/rtl8169.c b/drivers/rtl8169/rtl8169.c
index 8b84edcfd..a21298189 100644
--- a/drivers/rtl8169/rtl8169.c
+++ b/drivers/rtl8169/rtl8169.c
@@ -368,7 +368,6 @@ PRIVATE void sef_local_startup()
 PRIVATE int sef_cb_init_fresh(int type, sef_init_info_t *UNUSED(info))
 {
 /* Initialize the rtl8169 driver. */
-	int r;
 	re_t *rep;
 	long v;
 
diff --git a/drivers/tty/console.c b/drivers/tty/console.c
index 985f5608a..4c4975d78 100644
--- a/drivers/tty/console.c
+++ b/drivers/tty/console.c
@@ -965,7 +965,7 @@ tty_t *tp;
   /* Get the BIOS parameters that describe the VDU. */
   if (! vdu_initialized++) {
 
-	/* How about error checking? What to do on failure??? */
+	/* FIXME: How about error checking? What to do on failure??? */
   	s=sys_readbios(VDU_SCREEN_COLS_ADDR, &bios_columns,
 		VDU_SCREEN_COLS_SIZE);
   	s=sys_readbios(VDU_CRT_BASE_ADDR, &bios_crtbase,
diff --git a/kernel/system/do_safecopy.c b/kernel/system/do_safecopy.c
index 6cf85397a..ff4fd93e3 100644
--- a/kernel/system/do_safecopy.c
+++ b/kernel/system/do_safecopy.c
@@ -47,7 +47,7 @@ endpoint_t *e_granter;		/* new granter (magic grants) */
 	static cp_grant_t g;
 	static int proc_nr;
 	static const struct proc *granter_proc;
-	int r, depth = 0;
+	int depth = 0;
 
 	do {
 		/* Get granter process slot (if valid), and check range of
@@ -86,9 +86,9 @@ endpoint_t *e_granter;		/* new granter (magic grants) */
 		 * (presumably) set an invalid grant table entry by returning
 		 * EPERM, just like with an invalid grant id.
 		 */
-		if((r=data_copy(granter,
+		if(data_copy(granter,
 			priv(granter_proc)->s_grant_table + sizeof(g)*grant,
-			KERNEL, (vir_bytes) &g, sizeof(g))) != OK) {
+			KERNEL, (vir_bytes) &g, sizeof(g)) != OK) {
 			printf(
 			"verify_grant: grant verify: data_copy failed\n");
 			return EPERM;