diff --git a/sys/amd64/amd64/autoconf.c b/sys/amd64/amd64/autoconf.c
index 61d0abbcf068..b209065027d6 100644
--- a/sys/amd64/amd64/autoconf.c
+++ b/sys/amd64/amd64/autoconf.c
@@ -90,6 +90,10 @@ static void	configure_final __P((void *));
 static void	setroot __P((void));
 #endif
 
+#if defined(NFS) && defined(NFS_ROOT)
+static void	pxe_setup_nfsdiskless(void);
+#endif
+
 SYSINIT(configure1, SI_SUB_CONFIGURE, SI_ORDER_FIRST, configure_first, NULL);
 /* SI_ORDER_SECOND is hookable */
 SYSINIT(configure2, SI_SUB_CONFIGURE, SI_ORDER_THIRD, configure, NULL);
@@ -232,6 +236,7 @@ cpu_rootconf()
 #endif
 #if defined(NFS) && defined(NFS_ROOT)
 #if !defined(BOOTP_NFSROOT)
+	pxe_setup_nfsdiskless();
 	if (nfs_diskless_valid)
 #endif
 		rootdevnames[0] = "nfs:";
@@ -322,3 +327,172 @@ setroot()
 	sprintf(rootdevnames[1], "ufs:%s%s", sname, partname);
 }
 #endif
+
+#if defined(NFS) && defined(NFS_ROOT)
+
+#include <sys/socket.h>
+#include <net/if.h>
+#include <net/if_dl.h>
+#include <net/if_types.h>
+#include <net/if_var.h>
+#include <net/ethernet.h>
+#include <netinet/in.h>
+#include <nfs/rpcv2.h>
+#include <nfs/nfsproto.h>
+#include <nfs/nfs.h>
+#include <nfs/nfsdiskless.h>
+
+extern struct nfs_diskless	nfs_diskless;
+
+static int
+inaddr_to_sockaddr(char *ev, struct sockaddr_in *sa)
+{
+	u_int32_t	a[4];
+	char		*cp;
+
+	bzero(sa, sizeof(*sa));
+	sa->sin_len = sizeof(*sa);
+	sa->sin_family = AF_INET;
+
+	if ((cp = getenv(ev)) == NULL)
+		return(1);
+	if (sscanf(cp, "%d.%d.%d.%d", &a[0], &a[1], &a[2], &a[3]) != 4)
+		return(1);
+	/* XXX is this ordering correct? */
+	sa->sin_addr.s_addr = (a[3] << 24) + (a[2] << 16) + (a[1] << 8) + a[0];
+	return(0);
+}
+
+static int
+hwaddr_to_sockaddr(char *ev, struct sockaddr_dl *sa)
+{
+	char		*cp;
+	u_int32_t	a[6];
+
+	bzero(sa, sizeof(*sa));
+	sa->sdl_len = sizeof(*sa);
+	sa->sdl_family = AF_LINK;
+	sa->sdl_type = IFT_ETHER;
+	sa->sdl_alen = ETHER_ADDR_LEN;
+	if ((cp = getenv(ev)) == NULL)
+		return(1);
+	if (sscanf(cp, "%x:%x:%x:%x:%x:%x", &a[0], &a[1], &a[2], &a[3], &a[4], &a[5]) != 6)
+		return(1);
+	sa->sdl_data[0] = a[0];
+	sa->sdl_data[1] = a[1];
+	sa->sdl_data[2] = a[2];
+	sa->sdl_data[3] = a[3];
+	sa->sdl_data[4] = a[4];
+	sa->sdl_data[5] = a[5];
+	return(0);
+}
+
+static int
+decode_nfshandle(char *ev, u_char *fh) 
+{
+	u_char	*cp;
+	int	len, val;
+
+	if (((cp = getenv(ev)) == NULL) || (strlen(cp) < 2) || (*cp != 'X'))
+		return(0);
+	len = 0;
+	cp++;
+	for (;;) {
+		if (*cp == 'X')
+			return(len);
+		if ((sscanf(cp, "%2x", &val) != 1) || (val > 0xff))
+			return(0);
+		*(fh++) = val;
+		len++;
+		cp += 2;
+		if (len > NFSX_V2FH)
+		    return(0);
+	}
+}
+
+/*
+ * Populate the essential fields in the nfsv3_diskless structure.
+ *
+ * The loader is expected to export the following environment variables:
+ *
+ * boot.netif.ip		IP address on boot interface
+ * boot.netif.netmask		netmask on boot interface
+ * boot.netif.gateway		default gateway (optional)
+ * boot.netif.hwaddr		hardware address of boot interface
+ * boot.nfsroot.server		IP address of root filesystem server
+ * boot.nfsroot.path		path of the root filesystem on server
+ * boot.nfsroot.nfshandle	NFS handle for root filesystem on server
+ */
+static void
+pxe_setup_nfsdiskless()
+{
+	struct nfs_diskless	*nd = &nfs_diskless;
+	struct ifnet		*ifp;
+	struct ifaddr		*ifa;
+	struct sockaddr_dl	*sdl, ourdl;
+	struct sockaddr_in	myaddr, netmask;
+	char			*cp;
+
+	/* set up interface */
+	if (inaddr_to_sockaddr("boot.netif.ip", &myaddr))
+		return;
+	if (inaddr_to_sockaddr("boot.netif.netmask", &netmask)) {
+		printf("PXE: no netmask\n");
+		return;
+	}
+	bcopy(&myaddr, &nd->myif.ifra_addr, sizeof(myaddr));
+	bcopy(&myaddr, &nd->myif.ifra_broadaddr, sizeof(myaddr));
+	((struct sockaddr_in *) &nd->myif.ifra_broadaddr)->sin_addr.s_addr =
+		myaddr.sin_addr.s_addr | ~ netmask.sin_addr.s_addr;
+	bcopy(&netmask, &nd->myif.ifra_mask, sizeof(netmask));
+
+	if (hwaddr_to_sockaddr("boot.netif.hwaddr", &ourdl)) {
+		printf("PXE: no hardware address\n");
+		return;
+	}
+	ifa = NULL;
+	ifp = TAILQ_FIRST(&ifnet);
+	TAILQ_FOREACH(ifp, &ifnet, if_link) {
+		TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
+			if ((ifa->ifa_addr->sa_family == AF_LINK) &&
+			    (sdl = ((struct sockaddr_dl *)ifa->ifa_addr))) {
+				if ((sdl->sdl_type == ourdl.sdl_type) &&
+				    (sdl->sdl_alen == ourdl.sdl_alen) &&
+				    !bcmp(sdl->sdl_data + sdl->sdl_nlen,
+					  ourdl.sdl_data + ourdl.sdl_nlen, 
+					  sdl->sdl_alen))
+				    goto match_done;
+			}
+		}
+	}
+	printf("PXE: no interface\n");
+	return;	/* no matching interface */
+match_done:
+	sprintf(nd->myif.ifra_name, "%s%d", ifp->if_name, ifp->if_unit);
+
+	
+	/* set up gateway */
+	inaddr_to_sockaddr("boot.netif.gateway", &nd->mygateway);
+
+	/* XXX set up swap? */
+
+	/* set up root mount */
+	nd->root_args.rsize = 8192;		/* XXX tunable? */
+	nd->root_args.wsize = 8192;
+	nd->root_args.sotype = SOCK_DGRAM;
+	nd->root_args.flags = (NFSMNT_WSIZE | NFSMNT_RSIZE | NFSMNT_RESVPORT);
+	if (inaddr_to_sockaddr("boot.nfsroot.server", &nd->root_saddr)) {
+		printf("PXE: no server\n");
+		return;
+	}
+	nd->root_saddr.sin_port = htons(NFS_PORT);
+	if (decode_nfshandle("boot.nfsroot.nfshandle", &nd->root_fh[0]) == 0) {
+		printf("PXE: no NFS handle\n");
+		return;
+	}
+	if ((cp = getenv("boot.nfsroot.path")) != NULL)
+		strncpy(nd->root_hostnam, cp, MNAMELEN - 1);
+
+	nfs_diskless_valid = 1;
+}
+#endif
diff --git a/sys/i386/i386/autoconf.c b/sys/i386/i386/autoconf.c
index 61d0abbcf068..b209065027d6 100644
--- a/sys/i386/i386/autoconf.c
+++ b/sys/i386/i386/autoconf.c
@@ -90,6 +90,10 @@ static void	configure_final __P((void *));
 static void	setroot __P((void));
 #endif
 
+#if defined(NFS) && defined(NFS_ROOT)
+static void	pxe_setup_nfsdiskless(void);
+#endif
+
 SYSINIT(configure1, SI_SUB_CONFIGURE, SI_ORDER_FIRST, configure_first, NULL);
 /* SI_ORDER_SECOND is hookable */
 SYSINIT(configure2, SI_SUB_CONFIGURE, SI_ORDER_THIRD, configure, NULL);
@@ -232,6 +236,7 @@ cpu_rootconf()
 #endif
 #if defined(NFS) && defined(NFS_ROOT)
 #if !defined(BOOTP_NFSROOT)
+	pxe_setup_nfsdiskless();
 	if (nfs_diskless_valid)
 #endif
 		rootdevnames[0] = "nfs:";
@@ -322,3 +327,172 @@ setroot()
 	sprintf(rootdevnames[1], "ufs:%s%s", sname, partname);
 }
 #endif
+
+#if defined(NFS) && defined(NFS_ROOT)
+
+#include <sys/socket.h>
+#include <net/if.h>
+#include <net/if_dl.h>
+#include <net/if_types.h>
+#include <net/if_var.h>
+#include <net/ethernet.h>
+#include <netinet/in.h>
+#include <nfs/rpcv2.h>
+#include <nfs/nfsproto.h>
+#include <nfs/nfs.h>
+#include <nfs/nfsdiskless.h>
+
+extern struct nfs_diskless	nfs_diskless;
+
+static int
+inaddr_to_sockaddr(char *ev, struct sockaddr_in *sa)
+{
+	u_int32_t	a[4];
+	char		*cp;
+
+	bzero(sa, sizeof(*sa));
+	sa->sin_len = sizeof(*sa);
+	sa->sin_family = AF_INET;
+
+	if ((cp = getenv(ev)) == NULL)
+		return(1);
+	if (sscanf(cp, "%d.%d.%d.%d", &a[0], &a[1], &a[2], &a[3]) != 4)
+		return(1);
+	/* XXX is this ordering correct? */
+	sa->sin_addr.s_addr = (a[3] << 24) + (a[2] << 16) + (a[1] << 8) + a[0];
+	return(0);
+}
+
+static int
+hwaddr_to_sockaddr(char *ev, struct sockaddr_dl *sa)
+{
+	char		*cp;
+	u_int32_t	a[6];
+
+	bzero(sa, sizeof(*sa));
+	sa->sdl_len = sizeof(*sa);
+	sa->sdl_family = AF_LINK;
+	sa->sdl_type = IFT_ETHER;
+	sa->sdl_alen = ETHER_ADDR_LEN;
+	if ((cp = getenv(ev)) == NULL)
+		return(1);
+	if (sscanf(cp, "%x:%x:%x:%x:%x:%x", &a[0], &a[1], &a[2], &a[3], &a[4], &a[5]) != 6)
+		return(1);
+	sa->sdl_data[0] = a[0];
+	sa->sdl_data[1] = a[1];
+	sa->sdl_data[2] = a[2];
+	sa->sdl_data[3] = a[3];
+	sa->sdl_data[4] = a[4];
+	sa->sdl_data[5] = a[5];
+	return(0);
+}
+
+static int
+decode_nfshandle(char *ev, u_char *fh) 
+{
+	u_char	*cp;
+	int	len, val;
+
+	if (((cp = getenv(ev)) == NULL) || (strlen(cp) < 2) || (*cp != 'X'))
+		return(0);
+	len = 0;
+	cp++;
+	for (;;) {
+		if (*cp == 'X')
+			return(len);
+		if ((sscanf(cp, "%2x", &val) != 1) || (val > 0xff))
+			return(0);
+		*(fh++) = val;
+		len++;
+		cp += 2;
+		if (len > NFSX_V2FH)
+		    return(0);
+	}
+}
+
+/*
+ * Populate the essential fields in the nfsv3_diskless structure.
+ *
+ * The loader is expected to export the following environment variables:
+ *
+ * boot.netif.ip		IP address on boot interface
+ * boot.netif.netmask		netmask on boot interface
+ * boot.netif.gateway		default gateway (optional)
+ * boot.netif.hwaddr		hardware address of boot interface
+ * boot.nfsroot.server		IP address of root filesystem server
+ * boot.nfsroot.path		path of the root filesystem on server
+ * boot.nfsroot.nfshandle	NFS handle for root filesystem on server
+ */
+static void
+pxe_setup_nfsdiskless()
+{
+	struct nfs_diskless	*nd = &nfs_diskless;
+	struct ifnet		*ifp;
+	struct ifaddr		*ifa;
+	struct sockaddr_dl	*sdl, ourdl;
+	struct sockaddr_in	myaddr, netmask;
+	char			*cp;
+
+	/* set up interface */
+	if (inaddr_to_sockaddr("boot.netif.ip", &myaddr))
+		return;
+	if (inaddr_to_sockaddr("boot.netif.netmask", &netmask)) {
+		printf("PXE: no netmask\n");
+		return;
+	}
+	bcopy(&myaddr, &nd->myif.ifra_addr, sizeof(myaddr));
+	bcopy(&myaddr, &nd->myif.ifra_broadaddr, sizeof(myaddr));
+	((struct sockaddr_in *) &nd->myif.ifra_broadaddr)->sin_addr.s_addr =
+		myaddr.sin_addr.s_addr | ~ netmask.sin_addr.s_addr;
+	bcopy(&netmask, &nd->myif.ifra_mask, sizeof(netmask));
+
+	if (hwaddr_to_sockaddr("boot.netif.hwaddr", &ourdl)) {
+		printf("PXE: no hardware address\n");
+		return;
+	}
+	ifa = NULL;
+	ifp = TAILQ_FIRST(&ifnet);
+	TAILQ_FOREACH(ifp, &ifnet, if_link) {
+		TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
+			if ((ifa->ifa_addr->sa_family == AF_LINK) &&
+			    (sdl = ((struct sockaddr_dl *)ifa->ifa_addr))) {
+				if ((sdl->sdl_type == ourdl.sdl_type) &&
+				    (sdl->sdl_alen == ourdl.sdl_alen) &&
+				    !bcmp(sdl->sdl_data + sdl->sdl_nlen,
+					  ourdl.sdl_data + ourdl.sdl_nlen, 
+					  sdl->sdl_alen))
+				    goto match_done;
+			}
+		}
+	}
+	printf("PXE: no interface\n");
+	return;	/* no matching interface */
+match_done:
+	sprintf(nd->myif.ifra_name, "%s%d", ifp->if_name, ifp->if_unit);
+
+	
+	/* set up gateway */
+	inaddr_to_sockaddr("boot.netif.gateway", &nd->mygateway);
+
+	/* XXX set up swap? */
+
+	/* set up root mount */
+	nd->root_args.rsize = 8192;		/* XXX tunable? */
+	nd->root_args.wsize = 8192;
+	nd->root_args.sotype = SOCK_DGRAM;
+	nd->root_args.flags = (NFSMNT_WSIZE | NFSMNT_RSIZE | NFSMNT_RESVPORT);
+	if (inaddr_to_sockaddr("boot.nfsroot.server", &nd->root_saddr)) {
+		printf("PXE: no server\n");
+		return;
+	}
+	nd->root_saddr.sin_port = htons(NFS_PORT);
+	if (decode_nfshandle("boot.nfsroot.nfshandle", &nd->root_fh[0]) == 0) {
+		printf("PXE: no NFS handle\n");
+		return;
+	}
+	if ((cp = getenv("boot.nfsroot.path")) != NULL)
+		strncpy(nd->root_hostnam, cp, MNAMELEN - 1);
+
+	nfs_diskless_valid = 1;
+}
+#endif