[PATCH 2/2] support netbooting on JS21 GA3 and older firmwares

[Scott Moser]

  In order to support older firmware on setups where dhcp server has
  'next-server' set (so, dhcp server != tftp server), attempt to determine
  if this is a new firmware that supports full ftp.  If it is, then fill in
  the siaddr and ciaddr from the previous bootp request.
  
  The solution here just looks for the presense of /packages/cas in the OF.
  In all the systems that I have access to (power6, js22, js21,
  power5/squadron) this file exists on systems that have "true tftp"
  support.

  I realize this is by no means the best solution, but it does create a
  yaboot capable of network booting on all hardware that I have access
  to.  This includes power5 and power6 systems, and JS20, JS21 and a
  JS22 blades.  I'm posting it here mostly in hopes that it will both
  a.) give people a solution that have the same problem as myself, and
  b.) start a discussion on a better solution.

diff --git a/second/fs_of.c b/second/fs_of.c
index a9404f6..d0b2e5b 100644
--- a/second/fs_of.c
+++ b/second/fs_of.c
@@ -60,6 +60,8 @@ static int of_net_open(struct boot_file_t* file, const char* dev_name,
 static int of_net_read(struct boot_file_t* file, unsigned int size, void* buffer);
 static int of_net_seek(struct boot_file_t* file, unsigned int newpos);
 
+static int of_supports_real_tftp(void);
+static int of_net_use_tftp = -1;
 
 struct fs_t of_filesystem =
 {
@@ -131,6 +133,30 @@ of_open(struct boot_file_t* file, const char* dev_name,
      return FILE_ERR_OK;
 }
 
+/* 
+ *  older firmwares were really not capable of doing a tftp load.  Ie, the
+ *  'boot' command line: <device>:<siaddr>,<file>,<ciaddr> requires that
+ *  <siaddr> to be running a bootp server, not simply a tftp server.  The
+ *  above syntax works with new firmwares.
+ *
+ *  This function should return 1 if the running firmware fully supports
+ *  tftp and 0 if not.
+ */
+static int of_supports_real_tftp() {
+     prom_handle h;
+     if(of_net_use_tftp>=0) return(of_net_use_tftp);
+
+     h=prom_open("/packages/cas");
+     if(h) {
+          prom_close(h);
+          of_net_use_tftp=1;
+     } else {
+          of_net_use_tftp=0;
+     }
+     return(of_net_use_tftp);
+}
+
+
 static int
 of_net_open(struct boot_file_t* file, const char* dev_name,
 	    struct partition_t* part, const char* file_name)
@@ -143,24 +169,28 @@ of_net_open(struct boot_file_t* file, const char* dev_name,
      DEBUG_ENTER;
      DEBUG_OPEN;
 
-     packet = prom_get_netinfo();
 
      strncpy(buffer, dev_name, 768);
      if (file_name && strlen(file_name)) {
-	  strcat(buffer, prom_get_siaddr(packet));
+       if(of_supports_real_tftp()){
+          packet = prom_get_netinfo();
+	     strcat(buffer, prom_get_siaddr(packet));
+       }
 	  strcat(buffer, ",");
 	  filename = strdup(file_name);
 	  for (p = filename; *p; p++)
 	       if (*p == '/')
 		    *p = '\\';
 	  strcat(buffer, filename);
-	  strcat(buffer, ",");
-	  strcat(buffer, prom_get_yiaddr(packet));
-	  strcat(buffer, ",");
-	  /* Hack required since giaddr not returned on some systems
-	     and required to boot on those systems.  This should work
-	     for the client and server on the same subnet. */
-	  strcat(buffer, prom_get_siaddr(packet));
+       if(of_supports_real_tftp()) {
+	     strcat(buffer, ",");
+	     strcat(buffer, prom_get_yiaddr(packet));
+	     strcat(buffer, ",");
+	     /* Hack required since giaddr not returned on some systems
+	        and required to boot on those systems.  This should work
+	        for the client and server on the same subnet. */
+	     strcat(buffer, prom_get_siaddr(packet));
+       }
 	  free(filename);
      }