Can someone else please look over these patches ?  They appear to do the
right thing (including work).  My only real concern are alignment issues
with mbufs and some platforms, although BPF_ALIGN (see bpf_filter.c itself)
appears to take care of this(?).

Darren

p.s. I'm also cc'ing the tcpdump-workers list since this is a pretty
     fundamental change to boost performance.

*** /sys/net/bpf_filter.c.orig	Sun Dec  3 06:37:27 1995
--- /sys/net/bpf_filter.c	Sun Jun 18 16:40:25 2000
***************
*** 69,84 ****
  
  #ifdef KERNEL
  #include <sys/mbuf.h>
! #define MINDEX(m, k) \
  { \
! 	register int len = m->m_len; \
   \
! 	while (k >= len) { \
! 		k -= len; \
! 		m = m->m_next; \
! 		if (m == 0) \
  			return 0; \
! 		len = m->m_len; \
  	} \
  }
  
--- 69,84 ----
  
  #ifdef KERNEL
  #include <sys/mbuf.h>
! #define MINDEX(_m, _k) \
  { \
! 	register int _len = (_m)->m_len; \
   \
! 	while (_k >= _len) { \
! 		_k -= _len; \
! 		_m = (_m)->m_next; \
! 		if (_m == 0) \
  			return 0; \
! 		_len = (_m)->m_len; \
  	} \
  }
  
***************
*** 179,184 ****
--- 179,193 ----
  	register u_long A = 0, X = 0;
  	register int k;
  	long mem[BPF_MEMWORDS];
+ #ifdef 	KERNEL
+ 	struct mbuf *m = (struct mbuf *)p, *n;
+ 	int merr;
+ 
+ 	if (buflen == 0) {
+ 		p = mtod(m, char *);
+ 		buflen = m->m_len;
+ 	}
+ #endif
  
  	if (pc == 0)
  		/*
***************
*** 207,217 ****
  			k = pc->k;
  			if (k + sizeof(long) > buflen) {
  #ifdef KERNEL
! 				int merr;
! 
! 				if (buflen != 0)
! 					return 0;
! 				A = m_xword((struct mbuf *)p, k, &merr);
  				if (merr != 0)
  					return 0;
  				continue;
--- 216,222 ----
  			k = pc->k;
  			if (k + sizeof(long) > buflen) {
  #ifdef KERNEL
! 				A = m_xword(m, k, &merr);
  				if (merr != 0)
  					return 0;
  				continue;
***************
*** 231,241 ****
  			k = pc->k;
  			if (k + sizeof(short) > buflen) {
  #ifdef KERNEL
! 				int merr;
! 
! 				if (buflen != 0)
  					return 0;
- 				A = m_xhalf((struct mbuf *)p, k, &merr);
  				continue;
  #else
  				return 0;
--- 236,244 ----
  			k = pc->k;
  			if (k + sizeof(short) > buflen) {
  #ifdef KERNEL
! 				A = m_xhalf(m, k, &merr);
! 				if (merr != 0)
  					return 0;
  				continue;
  #else
  				return 0;
***************
*** 248,260 ****
  			k = pc->k;
  			if (k >= buflen) {
  #ifdef KERNEL
! 				register struct mbuf *m;
! 
! 				if (buflen != 0)
! 					return 0;
! 				m = (struct mbuf *)p;
! 				MINDEX(m, k);
! 				A = mtod(m, u_char *)[k];
  				continue;
  #else
  				return 0;
--- 251,259 ----
  			k = pc->k;
  			if (k >= buflen) {
  #ifdef KERNEL
! 				n = m;
! 				MINDEX(n, k);
! 				A = mtod(n, u_char *)[k];
  				continue;
  #else
  				return 0;
***************
*** 275,285 ****
  			k = X + pc->k;
  			if (k + sizeof(long) > buflen) {
  #ifdef KERNEL
! 				int merr;
! 
! 				if (buflen != 0)
! 					return 0;
! 				A = m_xword((struct mbuf *)p, k, &merr);
  				if (merr != 0)
  					return 0;
  				continue;
--- 274,280 ----
  			k = X + pc->k;
  			if (k + sizeof(long) > buflen) {
  #ifdef KERNEL
! 				A = m_xword(m, k, &merr);
  				if (merr != 0)
  					return 0;
  				continue;
***************
*** 299,309 ****
  			k = X + pc->k;
  			if (k + sizeof(short) > buflen) {
  #ifdef KERNEL
! 				int merr;
! 
! 				if (buflen != 0)
! 					return 0;
! 				A = m_xhalf((struct mbuf *)p, k, &merr);
  				if (merr != 0)
  					return 0;
  				continue;
--- 294,300 ----
  			k = X + pc->k;
  			if (k + sizeof(short) > buflen) {
  #ifdef KERNEL
! 				A = m_xhalf(m, k, &merr);
  				if (merr != 0)
  					return 0;
  				continue;
***************
*** 318,330 ****
  			k = X + pc->k;
  			if (k >= buflen) {
  #ifdef KERNEL
! 				register struct mbuf *m;
! 
! 				if (buflen != 0)
! 					return 0;
! 				m = (struct mbuf *)p;
! 				MINDEX(m, k);
! 				A = mtod(m, char *)[k];
  				continue;
  #else
  				return 0;
--- 309,317 ----
  			k = X + pc->k;
  			if (k >= buflen) {
  #ifdef KERNEL
! 				n = m;
! 				MINDEX(n, k);
! 				A = mtod(n, char *)[k];
  				continue;
  #else
  				return 0;
***************
*** 337,349 ****
  			k = pc->k;
  			if (k >= buflen) {
  #ifdef KERNEL
! 				register struct mbuf *m;
! 
! 				if (buflen != 0)
! 					return 0;
! 				m = (struct mbuf *)p;
! 				MINDEX(m, k);
! 				X = (mtod(m, char *)[k] & 0xf) << 2;
  				continue;
  #else
  				return 0;
--- 324,332 ----
  			k = pc->k;
  			if (k >= buflen) {
  #ifdef KERNEL
! 				n = m;
! 				MINDEX(n, k);
! 				X = (mtod(n, char *)[k] & 0xf) << 2;
  				continue;
  #else
  				return 0;