Merge branch 'pathbased' of ssh://terminus.zytor.com/pub/git/syslinux/syslinux into pathbasedsyslinux-4.00-pre50

15 files changed, 289 insertions, 52 deletions

diff --git a/com32/include/syslinux/config.h b/com32/include/syslinux/config.h
index 868b0f10..60d8d231 100644
--- a/com32/include/syslinux/config.h
+++ b/com32/include/syslinux/config.h
@@ -54,6 +54,14 @@ struct syslinux_version {
     const char *copyright_string;
 };
 
+struct syslinux_ipinfo {
+    uint32_t ipver;
+    uint32_t myip;
+    uint32_t netmask;
+    uint32_t gateway;
+    uint32_t serverip;
+};
+
 extern __nocommon struct syslinux_version __syslinux_version;
 static inline const struct syslinux_version *syslinux_version(void)
 {
@@ -116,6 +124,7 @@ union syslinux_derivative_info {
 	uint32_t _eflags;
 	const void *pxenvptr;
 	const void *stack;
+	const struct syslinux_ipinfo *ipinfo;
     } pxe;			/* pxelinux */
     struct {
 	uint16_t _gs, _fs, _es, _ds;
diff --git a/com32/sysdump/acpi.c b/com32/sysdump/acpi.c
new file mode 100644
index 00000000..48b890ae
--- /dev/null
+++ b/com32/sysdump/acpi.c
@@ -0,0 +1,175 @@
+/* ----------------------------------------------------------------------- *
+ *
+ *   Copyright 2010 Intel Corporation; author: H. Peter Anvin
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+ *   Boston MA 02110-1301, USA; either version 2 of the License, or
+ *   (at your option) any later version; incorporated herein by reference.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * Dump ACPI information
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include "sysdump.h"
+#include "backend.h"
+
+struct acpi_rsdp {
+    uint8_t  magic[8];		/* "RSD PTR " */
+    uint8_t  csum;
+    char     oemid[6];
+    uint8_t  rev;
+    uint32_t rsdt_addr;
+    uint32_t len;
+    uint64_t xdst_addr;
+    uint8_t  xcsum;
+    uint8_t  rsvd[3];
+};
+
+struct acpi_hdr {
+    char     sig[4];		/* Signature */
+    uint32_t len;
+    uint8_t  rev;
+    uint8_t  csum;
+    char     oemid[6];
+    char     oemtblid[16];
+    uint32_t oemrev;
+    uint32_t creatorid;
+    uint32_t creatorrev;
+};
+
+struct acpi_rsdt {
+    struct acpi_hdr hdr;
+    uint32_t entry[0];
+};
+
+enum tbl_errs {
+    ERR_NONE,			/* No errors */
+    ERR_CSUM,			/* Invalid checksum */
+    ERR_SIZE,			/* Impossibly large table */
+    ERR_NOSIG			/* No signature */
+};
+
+static uint8_t checksum_range(const void *start, uint32_t size)
+{
+    const uint8_t *p = start;
+    uint8_t csum = 0;
+
+    while (size--)
+	csum += *p++;
+
+    return csum;
+}
+
+static enum tbl_errs is_valid_table(const void *ptr)
+{
+    const struct acpi_hdr *hdr = ptr;
+
+    if (hdr->sig[0] == 0)
+	return ERR_NOSIG;
+
+    if (hdr->len < 10 || hdr->len > (1 << 20)) {
+	/* Either insane or too large to dump */
+	return ERR_SIZE;
+    }
+
+    return checksum_range(hdr, hdr->len) == 0 ? ERR_NONE : ERR_CSUM;
+}
+
+static const struct acpi_rsdp *scan_for_rsdp(uint32_t base, uint32_t end)
+{
+    for (base &= ~15; base < end-20; base += 16) {
+	const struct acpi_rsdp *rsdp = (const struct acpi_rsdp *)base;
+
+	if (memcmp(rsdp->magic, "RSD PTR ", 8))
+	    continue;
+
+	if (checksum_range(rsdp, 20))
+	    continue;
+
+	if (rsdp->rev > 0) {
+	    if (base + rsdp->len >= end ||
+		checksum_range(rsdp, rsdp->len))
+		continue;
+	}
+
+	return rsdp;
+    }
+
+    return NULL;
+}
+
+static const struct acpi_rsdp *find_rsdp(void)
+{
+    uint32_t ebda;
+    const struct acpi_rsdp *rsdp;
+
+    ebda = (*(uint16_t *)0x40e) << 4;
+    if (ebda >= 0x70000 && ebda < 0xa0000) {
+	rsdp = scan_for_rsdp(ebda, ebda+1024);
+
+	if (rsdp)
+	    return rsdp;
+    }
+
+    return scan_for_rsdp(0xe0000, 0x100000);
+}
+
+static void dump_table(struct backend *be,
+		       const char name[], const void *ptr, uint32_t len)
+{
+    char namebuf[64];
+
+    /* XXX: this make cause the same directory to show up more than once */
+    snprintf(namebuf, sizeof namebuf, "acpi/%4.4s", name);
+    cpio_mkdir(be, namebuf);
+
+    snprintf(namebuf, sizeof namebuf, "acpi/%4.4s/%08x", name, (uint32_t)ptr);
+    cpio_hdr(be, MODE_FILE, len, namebuf);
+
+    write_data(be, ptr, len);
+}
+
+void dump_acpi(struct backend *be)
+{
+    const struct acpi_rsdp *rsdp;
+    const struct acpi_rsdt *rsdt;
+    uint32_t rsdp_len;
+    uint32_t i, n;
+
+    rsdp = find_rsdp();
+
+    if (!rsdp)
+	return;			/* No ACPI information found */
+
+    cpio_mkdir(be, "acpi");
+
+    rsdp_len = rsdp->rev > 0 ? rsdp->len : 20;
+
+    dump_table(be, "RSDP", rsdp, rsdp_len);
+
+    rsdt = (const struct acpi_rsdt *)rsdp->rsdt_addr;
+
+    if (memcmp(rsdt->hdr.sig, "RSDT", 4) || is_valid_table(rsdt) != ERR_NONE)
+	return;
+
+    dump_table(be, rsdt->hdr.sig, rsdt, rsdt->hdr.len);
+
+    if (rsdt->hdr.len < 36)
+	return;
+
+    n = (rsdt->hdr.len - 36) >> 2;
+
+    for (i = 0; i < n; i++) {
+	const struct acpi_hdr *hdr = (const struct acpi_hdr *)(rsdt->entry[i]);
+
+	if (is_valid_table(hdr) <= ERR_CSUM)
+	    dump_table(be, hdr->sig, hdr, hdr->len);
+    }
+}
diff --git a/com32/sysdump/be_tftp.c b/com32/sysdump/be_tftp.c
index 07fdb084..8c92d4d6 100644
--- a/com32/sysdump/be_tftp.c
+++ b/com32/sysdump/be_tftp.c
@@ -21,23 +21,30 @@ enum tftp_opcode {
 struct tftp_state {
     uint32_t my_ip;
     uint32_t srv_ip;
+    uint32_t srv_gw;
     uint16_t my_port;
     uint16_t srv_port;
     uint16_t seq;
 };
 
+#define RCV_BUF	2048
+
 static int send_ack_packet(struct tftp_state *tftp,
 			   const void *pkt, size_t len)
 {
     com32sys_t ireg, oreg;
-    t_PXENV_UDP_WRITE *uw = __com32.cs_bounce;
-    t_PXENV_UDP_READ  *ur = __com32.cs_bounce;
+    t_PXENV_UDP_WRITE *uw;
+    t_PXENV_UDP_READ  *ur;
     clock_t start;
     static const clock_t timeouts[] = {
 	2, 2, 3, 3, 4, 5, 6, 7, 9, 10, 12, 15, 18, 21, 26, 31,
 	37, 44, 53, 64, 77, 92, 110, 132, 159, 191, 229, 0
     };
     const clock_t *timeout;
+    int err = -1;
+
+    uw = lmalloc(sizeof *uw + len);
+    ur = lmalloc(sizeof *ur + RCV_BUF);
 
     memset(&ireg, 0, sizeof ireg);
     ireg.eax.w[0] = 0x0009;
@@ -46,6 +53,7 @@ static int send_ack_packet(struct tftp_state *tftp,
 	memset(uw, 0, sizeof uw);
 	memcpy(uw+1, pkt, len);
 	uw->ip = tftp->srv_ip;
+	uw->gw = tftp->srv_gw;
 	uw->src_port = tftp->my_port;
 	uw->dst_port = tftp->srv_port ? tftp->srv_port : htons(69);
 	uw->buffer_size = len;
@@ -65,7 +73,7 @@ static int send_ack_packet(struct tftp_state *tftp,
 	    ur->dest_ip = tftp->my_ip;
 	    ur->s_port = tftp->srv_port;
 	    ur->d_port = tftp->my_port;
-	    ur->buffer_size = __com32.cs_bounce_size - sizeof *ur;
+	    ur->buffer_size = RCV_BUF;
 	    ur->buffer = FAR_PTR(ur+1);
 
 	    ireg.ebx.w[0] = PXENV_UDP_READ;
@@ -82,15 +90,20 @@ static int send_ack_packet(struct tftp_state *tftp,
 		if (ntohs(xb[0]) == TFTP_ACK &&
 		    ntohs(xb[1]) == tftp->seq) {
 		    tftp->srv_port = ur->s_port;
-		    return 0;		/* All good! */
+		    err = 0;		/* All good! */
+		    goto done;
 		} else if (ntohs(xb[1]) == TFTP_ERROR) {
-		    return -1;		/* All bad! */
+		    goto done;
 		}
 	    }
 	} while ((clock_t)(times(NULL) - start) < *timeout);
     }
 
-    return -1;			/* No success... */
+done:
+    lfree(ur);
+    lfree(uw);
+
+    return err;
 }
 
 static int be_tftp_write(struct backend *be)
@@ -108,6 +121,8 @@ static int be_tftp_write(struct backend *be)
     tftp.my_ip    = sdi->pxe.myip;
     tftp.my_port  = htons(local_port++);
     tftp.srv_ip   = pxe_dns(be->argv[1]);
+    tftp.srv_gw   = ((tftp.srv_ip ^ tftp.my_ip) & sdi->pxe.ipinfo->netmask)
+	? sdi->pxe.ipinfo->gateway : 0;
     tftp.srv_port = 0;
     tftp.seq      = 0;
 
diff --git a/com32/sysdump/main.c b/com32/sysdump/main.c
index d4a0320e..26f562be 100644
--- a/com32/sysdump/main.c
+++ b/com32/sysdump/main.c
@@ -41,6 +41,7 @@ static void dump_all(struct backend *be, const char *argv[])
     dump_memory_map(be);
     dump_memory(be);
     dump_dmi(be);
+    dump_acpi(be);
     dump_cpuid(be);
     dump_pci(be);
     dump_vesa_tables(be);
diff --git a/com32/sysdump/memmap.c b/com32/sysdump/memmap.c
index a85f0925..251107d5 100644
--- a/com32/sysdump/memmap.c
+++ b/com32/sysdump/memmap.c
@@ -19,10 +19,12 @@ struct e820_info {
 static void dump_e820(struct backend *be)
 {
     com32sys_t ireg, oreg;
-    struct e820_info *curr = __com32.cs_bounce;
+    struct e820_info *curr;
     struct e820_info *buf, *p;
     int nentry, nalloc;
 
+    curr = lmalloc(sizeof *curr);
+
     buf = p = NULL;
     nentry = nalloc = 0;
     memset(&ireg, 0, sizeof ireg);
@@ -56,7 +58,9 @@ static void dump_e820(struct backend *be)
 
     if (nentry)
 	cpio_writefile(be, "memmap/15e820", buf, nentry*sizeof *buf);
+
     free(buf);
+    lfree(curr);
 }
 
 void dump_memory_map(struct backend *be)
diff --git a/com32/sysdump/sysdump.h b/com32/sysdump/sysdump.h
index 61a04a2b..a5b963f8 100644
--- a/com32/sysdump/sysdump.h
+++ b/com32/sysdump/sysdump.h
@@ -7,6 +7,7 @@ void dump_memory_map(struct backend *);
 void snapshot_lowmem(void);
 void dump_memory(struct backend *);
 void dump_dmi(struct backend *);
+void dump_acpi(struct backend *);
 void dump_cpuid(struct backend *);
 void dump_pci(struct backend *);
 void dump_vesa_tables(struct backend *);
diff --git a/com32/sysdump/vesa.c b/com32/sysdump/vesa.c
index 9bdc7153..017f9e4f 100644
--- a/com32/sysdump/vesa.c
+++ b/com32/sysdump/vesa.c
@@ -7,6 +7,7 @@
 void dump_vesa_tables(struct backend *be)
 {
     com32sys_t rm;
+    struct vesa_info *vip;
     struct vesa_general_info *gip, gi;
     struct vesa_mode_info *mip, mi;
     uint16_t mode, *mode_ptr;
@@ -15,8 +16,9 @@ void dump_vesa_tables(struct backend *be)
     printf("Scanning VESA BIOS... ");
 
     /* Allocate space in the bounce buffer for these structures */
-    gip = &((struct vesa_info *)__com32.cs_bounce)->gi;
-    mip = &((struct vesa_info *)__com32.cs_bounce)->mi;
+    vip = lmalloc(sizeof *vip);
+    gip = &vip->gi;
+    mip = &vip->mi;
 
     memset(&rm, 0, sizeof rm);
     memset(gip, 0, sizeof *gip);
@@ -56,5 +58,6 @@ void dump_vesa_tables(struct backend *be)
 	cpio_writefile(be, modefile, &mi, sizeof mi);
     }
 
+    lfree(vip);
     printf("done.\n");
 }
diff --git a/core/comboot.inc b/core/comboot.inc
index 45b770f3..0c9956a0 100644
--- a/core/comboot.inc
+++ b/core/comboot.inc
@@ -580,8 +580,10 @@ comapi_derinfo:
 		mov P_SI,ax
 		mov ax,[InitStack+2]
 		mov P_FS,ax
-		mov eax,[MyIP]
+		mov eax,[IPInfo.MyIP]
 		mov P_ECX,eax
+		mov P_GS,0
+		mov P_DI,IPInfo
 %else
 		; Physical medium...
 
diff --git a/core/fs/pxe/dhcp_option.c b/core/fs/pxe/dhcp_option.c
index e18b605d..39b51666 100644
--- a/core/fs/pxe/dhcp_option.c
+++ b/core/fs/pxe/dhcp_option.c
@@ -16,14 +16,14 @@ static void subnet_mask(void *data, int opt_len)
 {
     if (opt_len != 4)
 	return;
-    net_mask = *(uint32_t *)data;
+    IPInfo.netmask = *(uint32_t *)data;
 }
 
 static void router(void *data, int opt_len)
 {
     if (opt_len != 4)
 	return;
-    gate_way = *(uint32_t *)data;
+    IPInfo.gateway = *(uint32_t *)data;
 }
 
 static void dns_servers(void *data, int opt_len)
@@ -83,12 +83,12 @@ static void server(void *data, int opt_len)
     if (opt_len != 4)
 	return;
     
-    if (server_ip)
+    if (IPInfo.serverip)
         return;
     
     ip = *(uint32_t *)data;
     if (ip_ok(ip))
-        server_ip = ip;
+        IPInfo.serverip = ip;
 }
 
 static void client_identifier(void *data, int opt_len)
@@ -246,10 +246,10 @@ void parse_dhcp(int pkt_len)
 
     over_load = 0;
     if (ip_ok(dhcp->yip))
-        MyIP = dhcp->yip;
+        IPInfo.myip = dhcp->yip;
     
     if (ip_ok(dhcp->sip))
-        server_ip = dhcp->sip;
+        IPInfo.serverip = dhcp->sip;
     
     opt_len = (char *)dhcp + pkt_len - (char *)&dhcp->options;
     if (opt_len && (dhcp->option_magic == BOOTP_OPTION_MAGIC)) 
diff --git a/core/fs/pxe/dnsresolv.c b/core/fs/pxe/dnsresolv.c
index df7f33c1..134f24e3 100644
--- a/core/fs/pxe/dnsresolv.c
+++ b/core/fs/pxe/dnsresolv.c
@@ -229,7 +229,7 @@ uint32_t dns_resolv(const char *name)
 	    continue;  /* just move on before runing the time out */
         udp_write.status      = 0;
         udp_write.ip          = srv;
-        udp_write.gw          = ((srv ^ MyIP) & net_mask) ? gate_way : 0;
+        udp_write.gw          = gateway(srv);
         udp_write.src_port    = local_port;
         udp_write.dst_port    = DNS_PORT;
         udp_write.buffer_size = p - DNSSendBuf;
@@ -242,7 +242,7 @@ uint32_t dns_resolv(const char *name)
 	while (1) {
             udp_read.status      = 0;
             udp_read.src_ip      = srv;
-            udp_read.dest_ip     = MyIP;
+            udp_read.dest_ip     = IPInfo.myip;
             udp_read.s_port      = DNS_PORT;
             udp_read.d_port      = local_port;
             udp_read.buffer_size = DNS_MAX_PACKET;
diff --git a/core/fs/pxe/idle.c b/core/fs/pxe/idle.c
index 0538b163..52a87c34 100644
--- a/core/fs/pxe/idle.c
+++ b/core/fs/pxe/idle.c
@@ -27,7 +27,7 @@ static int pxe_idle_poll(void)
     memset(&read_buf, 0, sizeof read_buf);
 
     read_buf.src_ip  = 0;	 /* Any destination */
-    read_buf.dest_ip = MyIP;
+    read_buf.dest_ip = IPInfo.myip;
     read_buf.s_port  = 0;	 /* Any source port */
     read_buf.d_port  = htons(9); /* Discard port (not used...) */
     read_buf.buffer_size = sizeof junk_pkt;
diff --git a/core/fs/pxe/pxe.c b/core/fs/pxe/pxe.c
index 011ef293..ef2398b4 100644
--- a/core/fs/pxe/pxe.c
+++ b/core/fs/pxe/pxe.c
@@ -9,10 +9,7 @@
 
 #define GPXE 1
 
-uint32_t server_ip = 0;            /* IP address of boot server */
-uint32_t net_mask = 0;             /* net_mask of this subnet */
-uint32_t gate_way = 0;             /* Default router */
-uint16_t real_base_mem;            /* Amount of DOS memory after freeing */
+static uint16_t real_base_mem;	   /* Amount of DOS memory after freeing */
 
 uint8_t MAC[MAC_MAX];		   /* Actual MAC address */
 uint8_t MAC_len;                   /* MAC address len */
@@ -297,7 +294,7 @@ static void tftp_error(struct inode *inode, uint16_t errnum,
     udp_write.src_port    = socket->tftp_localport;
     udp_write.dst_port    = socket->tftp_remoteport;
     udp_write.ip          = socket->tftp_remoteip;
-    udp_write.gw          = ((udp_write.ip ^ MyIP) & net_mask) ? gate_way : 0;
+    udp_write.gw          = gateway(udp_write.ip);
     udp_write.buffer      = FAR_PTR(&err_buf);
     udp_write.buffer_size = 4 + len + 1;
 
@@ -326,7 +323,7 @@ static void ack_packet(struct inode *inode, uint16_t ack_num)
     udp_write.src_port    = socket->tftp_localport;
     udp_write.dst_port    = socket->tftp_remoteport;
     udp_write.ip          = socket->tftp_remoteip;
-    udp_write.gw          = ((udp_write.ip ^ MyIP) & net_mask) ? gate_way : 0;
+    udp_write.gw          = gateway(udp_write.ip);
     udp_write.buffer      = FAR_PTR(ack_packet_buf);
     udp_write.buffer_size = 4;
 
@@ -513,7 +510,7 @@ static void fill_buffer(struct inode *inode)
         udp_read.buffer      = FAR_PTR(packet_buf);
         udp_read.buffer_size = PKTBUF_SIZE;
         udp_read.src_ip      = socket->tftp_remoteip;
-        udp_read.dest_ip     = MyIP;
+        udp_read.dest_ip     = IPInfo.myip;
         udp_read.s_port      = socket->tftp_remoteport;
         udp_read.d_port      = socket->tftp_localport;
         err = pxe_call(PXENV_UDP_READ, &udp_read);
@@ -688,12 +685,12 @@ static void pxe_searchdir(const char *filename, struct file *file)
     case PXE_RELATIVE:		/* Really shouldn't happen... */
     case PXE_URL:
 	buf = stpcpy(buf, filename);
-	ip = server_ip;		/* Default server */
+	ip = IPInfo.serverip;	/* Default server */
 	break;
 
     case PXE_HOMESERVER:
 	buf = stpcpy(buf, filename+2);
-	ip = server_ip;
+	ip = IPInfo.serverip;
 	break;
 
     case PXE_TFTP:
@@ -781,7 +778,7 @@ sendreq:
     tid = socket->tftp_localport;   /* TID(local port No) */
     udp_write.buffer    = FAR_PTR(rrq_packet_buf);
     udp_write.ip        = ip;
-    udp_write.gw        = ((udp_write.ip ^ MyIP) & net_mask) ? gate_way : 0;
+    udp_write.gw        = gateway(udp_write.ip);
     udp_write.src_port  = tid;
     udp_write.dst_port  = server_port;
     udp_write.buffer_size = buf - rrq_packet_buf;
@@ -794,7 +791,7 @@ wait_pkt:
         buf                  = packet_buf;
         udp_read.buffer      = FAR_PTR(buf);
         udp_read.buffer_size = PKTBUF_SIZE;
-        udp_read.dest_ip     = MyIP;
+        udp_read.dest_ip     = IPInfo.myip;
         udp_read.d_port      = tid;
         err = pxe_call(PXENV_UDP_READ, &udp_read);
         if (err) {
@@ -1107,7 +1104,7 @@ static int pxe_load_config(void)
         return 0;
 
     /* Nope, try hexadecimal IP prefixes... */
-    uchexbytes(config_file, (uint8_t *)&MyIP, 4);     /* Convet to hex string */
+    uchexbytes(config_file, (uint8_t *)&IPInfo.myip, 4);     /* Convet to hex string */
     last = &config_file[8];
     while (tries) {
         *last = '\0';        /* Zero-terminate string */
@@ -1151,26 +1148,23 @@ char __bss16 IPOption[3+4*16];
 static void genipopt(void)
 {
     char *p = IPOption;
+    const uint32_t *v = &IPInfo.myip;
+    int i;
 
     p = stpcpy(p, "ip=");
 
-    p += gendotquad(p, MyIP);
-    *p++ = ':';
-
-    p += gendotquad(p, server_ip);
-    *p++ = ':';
-
-    p += gendotquad(p, gate_way);
-    *p++ = ':';
-
-    gendotquad(p, net_mask);
+    for (i = 0; i < 4; i++) {
+	p += gendotquad(p, *v++);
+	*p++ = ':';
+    }
+    *--p = '\0';
 }
 
 
 /* Generate ip= option and print the ip adress */
 static void ip_init(void)
 {
-    uint32_t ip = MyIP;
+    uint32_t ip = IPInfo.myip;
 
     genipopt();
     gendotquad(dot_quad_buf, ip);
@@ -1412,7 +1406,7 @@ static void udp_init(void)
 {
     int err;
     static __lowmem struct s_PXENV_UDP_OPEN udp_open;
-    udp_open.src_ip = MyIP;
+    udp_open.src_ip = IPInfo.myip;
     err = pxe_call(PXENV_UDP_OPEN, &udp_open);
     if (err || udp_open.status) {
         printf("Failed to initialize UDP stack ");
diff --git a/core/fs/pxe/pxe.h b/core/fs/pxe/pxe.h
index e801aea5..cad63507 100644
--- a/core/fs/pxe/pxe.h
+++ b/core/fs/pxe/pxe.h
@@ -170,13 +170,20 @@ struct pxe_pvt_inode {
 #define PVT(i) ((struct pxe_pvt_inode *)((i)->pvt))
 
 /*
+ * Network boot information
+ */
+struct ip_info {
+    uint32_t ipv4;
+    uint32_t myip;
+    uint32_t serverip;
+    uint32_t gateway;
+    uint32_t netmask;
+};
+
+/*
  * Variable externs
  */
-extern uint32_t server_ip;
-extern uint32_t MyIP;
-extern uint32_t net_mask;
-extern uint32_t gate_way;
-extern uint16_t server_port;
+extern struct ip_info IPInfo;
 
 extern uint8_t MAC[];
 extern char BOOTIFStr[];
@@ -195,7 +202,6 @@ extern char dot_quad_buf[];
 
 extern uint32_t dns_server[];
 
-extern uint16_t real_base_mem;
 extern uint16_t APIVer;
 extern far_ptr_t PXEEntry;
 extern uint8_t KeepPXE;
@@ -209,6 +215,17 @@ extern char uuid[];
 extern uint16_t BIOS_fbm;
 extern const uint8_t TimeoutTable[];
 
+/*
+ * Compute the suitable gateway for a specific route -- too many
+ * vendor PXE stacks don't do this correctly...
+ */
+static inline uint32_t gateway(uint32_t ip)
+{
+    if ((ip ^ IPInfo.myip) & IPInfo.netmask)
+	return IPInfo.gateway;
+    else
+	return 0;
+}
 
 /*
  * functions 
diff --git a/core/pxelinux.asm b/core/pxelinux.asm
index 0b87e735..6fb77c25 100644
--- a/core/pxelinux.asm
+++ b/core/pxelinux.asm
@@ -530,7 +530,15 @@ exten_table_end:
 KeepPXE		db 0			; Should PXE be kept around?
 
 ;
-; IP information (initialized to "unknown" values)
+; IP information.  Note that the field are in the same order as the
+; Linux kernel expects in the ip= option.
+;
+		section .bss16
 		alignz 4
-                global MyIP
-MyIP		dd 0			; My IP address 
+		global IPInfo
+IPInfo:
+.IPv4		resd 1			; IPv4 information
+.MyIP		resd 1			; My IP address 
+.ServerIP	resd 1
+.GatewayIP	resd 1
+.Netmask	resd 1
diff --git a/doc/comboot.txt b/doc/comboot.txt
index f39d7243..036bd784 100644
--- a/doc/comboot.txt
+++ b/doc/comboot.txt
@@ -448,6 +448,7 @@ AX=000Ah [2.00]	Get Derivative-Specific Information
 		ECX	Local IP number (network byte order) [3.85]
 		ES:BX	pointer to PXENV+ or !PXE structure
 		FS:SI	pointer to original stack with invocation record
+		GS:DI	pointer to network information [4.00]
 
 		Note: DX notes the API version detected by PXELINUX,
 		which may be more conservative than the actual version
@@ -481,6 +482,13 @@ AX=000Ah [2.00]	Get Derivative-Specific Information
 		[fs:si+44]	PXE return IP	<- t.o.s. when PXELINUX invoked
 		[fs:si+46]	PXE return CS
 
+		GS:DI points to a structure of the following form:
+
+		[gs:di+0]	4		- IPv4
+		[gs:di+4]	My IP
+		[gs:di+8]	Boot server IP
+		[gs:di+12]	Gateway IP
+		[gs:di+16]	Netmask
 
 	[ISOLINUX]
 	Input:	AX	000Ah