Modify boot-conf so it can take a kernel or directory name as

a parameter and dtrt.

Also, make boot-conf always unload first. There wasn't really any
point in not doing this, as the kernel _has_ to be loaded before
any other modules.

Tested by: dwhite

sys/boot/forth/loader.4th

@@ -32,11 +32,129 @@ only forth definitions also support-functions
 \
 \	Prepares to boot as specified by loaded configuration files.
 
-: boot-conf
-  load_kernel
-  load_modules
-  0 autoboot
+also support-functions definitions
+
+: bootpath s" /boot/" ;
+: modulepath s" module_path" ;
+: saveenv ( addr len | 0 -1 -- addr' len | 0 -1 )
+  dup -1 = if exit then
+  dup allocate abort" Out of memory"
+  swap 2dup 2>r
+  move
+  2r>
 ;
+: freeenv ( addr len | 0 -1 )
+  -1 = if drop else free abort" Freeing error" then
+;
+: restoreenv  ( addr len | 0 -1 -- )
+  dup -1 = if ( it wasn't set )
+    2drop
+    modulepath unsetenv
+  else
+    over >r
+    modulepath setenv
+    r> free abort" Freeing error"
+  then
+;
+
+only forth also support-functions also builtins definitions
+
+: boot-conf  ( args 1 | 0 "args" -- flag )
+  0 1 unload drop
+
+  0= if ( interpreted )
+    \ Get next word on the command line
+    bl word count
+    ?dup 0= if ( there wasn't anything )
+      drop 0
+    else ( put in the number of strings )
+      1
+    then
+  then ( interpreted )
+
+  if ( there are arguments )
+    \ Try to load the kernel
+    s" kernel_options" getenv dup -1 = if drop 2dup 1 else 2over 2 then
+
+    1 load if ( load command failed )
+      \ Remove garbage from the stack
+
+      \ Set the environment variable module_path, and try loading
+      \ the kernel again.
+
+      \ First, save module_path value
+      modulepath getenv saveenv dup -1 = if 0 swap then 2>r
+
+      \ Sets the new value
+      2dup modulepath setenv
+
+      \ Try to load the kernel
+      s" load ${kernel} ${kernel_options}" ['] evaluate catch
+      if ( load failed yet again )
+	\ Remove garbage from the stack
+	2drop
+
+	\ Try prepending /boot/
+	bootpath 2over nip over + allocate
+	if ( out of memory )
+	  2drop 2drop
+	  2r> restoreenv
+	  100 exit
+	then
+
+	0 2swap strcat 2swap strcat
+	2dup modulepath setenv
+
+	drop free if ( freeing memory error )
+	  2drop
+	  2r> restoreenv
+	  100 exit
+	then
+ 
+	\ Now, once more, try to load the kernel
+	s" load ${kernel} ${kernel_options}" ['] evaluate catch
+	if ( failed once more )
+	  2drop
+	  2r> restoreenv
+	  100 exit
+	then
+
+      else ( we found the kernel on the path passed )
+
+	2drop ( discard command line arguments )
+
+      then ( could not load kernel from directory passed )
+
+      \ Load the remaining modules, if the kernel was loaded at all
+      ['] load_modules catch if 2r> restoreenv 100 exit then
+
+      \ Call autoboot to perform the booting
+      0 1 autoboot
+
+      \ Keep new module_path
+      2r> freeenv
+
+      exit
+    then ( could not load kernel with name passed )
+
+    2drop ( discard command line arguments )
+
+  else ( try just a straight-forward kernel load )
+    s" load ${kernel} ${kernel_options}" ['] evaluate catch
+    if ( kernel load failed ) 2drop 100 exit then
+
+  then ( there are command line arguments )
+
+  \ Load the remaining modules, if the kernel was loaded at all
+  ['] load_modules catch if 100 exit then
+
+  \ Call autoboot to perform the booting
+  0 1 autoboot
+;
+
+also forth definitions
+builtin: boot-conf
+only forth definitions also support-functions
 
 \ ***** check-password
 \