diff --git a/c/src/lib/libbsp/m68k/dmv152/startup/linkcmds b/c/src/lib/libbsp/m68k/dmv152/startup/linkcmds
index 7f92758e77..8edc69ee94 100644
--- a/c/src/lib/libbsp/m68k/dmv152/startup/linkcmds
+++ b/c/src/lib/libbsp/m68k/dmv152/startup/linkcmds
@@ -15,6 +15,8 @@
 /*
  * Declare some sizes.
  */
+_RamBase = DEFINED(_RamBase) ? _RamBase : 0x0;
+_RamSize = DEFINED(_RamSize) ? _RamSize : 1M;
 _HeapSize = DEFINED(_HeapSize) ? _HeapSize : 0x10000;
 _StackSize = DEFINED(_StackSize) ? _StackSize : 0x1000;
 
@@ -23,9 +25,6 @@ MEMORY
 	ram : org = 0x0, l = 1M
 }
 
-_RamBase = 0;
-_RamSize = 1M;
-
 SECTIONS
 {
 	ram : {
diff --git a/c/src/lib/libbsp/m68k/efi332/startup/linkcmds b/c/src/lib/libbsp/m68k/efi332/startup/linkcmds
index 6ac7ee77a4..7133fafa8b 100644
--- a/c/src/lib/libbsp/m68k/efi332/startup/linkcmds
+++ b/c/src/lib/libbsp/m68k/efi332/startup/linkcmds
@@ -33,6 +33,8 @@ __DYNAMIC  =  0;
 /*
  * Declare some sizes.
  */
+_RamBase = DEFINED(_RamBase) ? _RamBase : 0x80000;
+_RamSize = DEFINED(_RamSize) ? _RamSize : 0x80000;
 _HeapSize = DEFINED(_HeapSize) ? _HeapSize : 0x10000;
 _StackSize = DEFINED(_StackSize) ? _StackSize : 0x1000;
 
@@ -41,9 +43,6 @@ MEMORY
   ram     : ORIGIN = 0x80000, LENGTH = 512K
 }
 
-_RamBase = 0x80000;
-_RamSize = 0x80000;
-
 __end_of_ram = 0x100000;
 _copy_data_from_rom = 0;
 
diff --git a/c/src/lib/libbsp/m68k/efi332/startup/linkcmds_ROM b/c/src/lib/libbsp/m68k/efi332/startup/linkcmds_ROM
index b4f3bf70b1..acfee4c07f 100644
--- a/c/src/lib/libbsp/m68k/efi332/startup/linkcmds_ROM
+++ b/c/src/lib/libbsp/m68k/efi332/startup/linkcmds_ROM
@@ -43,6 +43,8 @@ MEMORY
   ram     : ORIGIN = 0x80000, LENGTH = 512K
 }
 
+_RamBase = DEFINED(_RamBase) ? _RamBase : 0x080000;
+
 __end_of_ram = 0x100000;
 _copy_data_from_rom = 1;
 
diff --git a/c/src/lib/libbsp/m68k/efi68k/startup/linkcmds b/c/src/lib/libbsp/m68k/efi68k/startup/linkcmds
index c174c3f4c8..4830c948d7 100644
--- a/c/src/lib/libbsp/m68k/efi68k/startup/linkcmds
+++ b/c/src/lib/libbsp/m68k/efi68k/startup/linkcmds
@@ -42,9 +42,6 @@ MEMORY
   ram     : ORIGIN = 0x203000, LENGTH = 256K
 }
 
-_RamBase = 0x200000;
-_RamSize = 256K;
-
 _VBR = 0x200000;		/* location of the VBR table (in RAM) */
 __end_of_ram = 0x240000;
 _copy_data_from_rom = 0;
@@ -52,6 +49,8 @@ _copy_data_from_rom = 0;
 /*
  * Declare some sizes.
  */
+_RamBase = DEFINED(_RamBase) ? _RamBase : 0x200000;
+_RamSize = DEFINED(_RamSize) ? _RamSize : 256K;
 _HeapSize = DEFINED(_HeapSize) ? _HeapSize : 0x10000;
 _StackSize = DEFINED(_StackSize) ? _StackSize : 0x1000;
 
diff --git a/c/src/lib/libbsp/m68k/gen68302/startup/linkcmds b/c/src/lib/libbsp/m68k/gen68302/startup/linkcmds
index 99d0f27cac..64bbcad42f 100644
--- a/c/src/lib/libbsp/m68k/gen68302/startup/linkcmds
+++ b/c/src/lib/libbsp/m68k/gen68302/startup/linkcmds
@@ -17,15 +17,14 @@ MEMORY
 	ram : org = 0x0000, l = 16M
 }
 
-_RamBase = 0;
-_RamSize = 16M;
-
 m302 = 0xf7f000;
 _VBR = 0x000000;		/* location of the VBR table (in RAM) */
 
 /*
  * Declare some sizes.
  */
+_RamBase = DEFINED(_RamBase) ? _RamBase : 0x0;
+_RamSize = DEFINED(_RamSize) ? _RamSize : 16M;
 _HeapSize = DEFINED(_HeapSize) ? _HeapSize : 0x10000;
 _StackSize = DEFINED(_StackSize) ? _StackSize : 0x1000;
 
diff --git a/c/src/lib/libbsp/m68k/gen68340/startup/linkcmds b/c/src/lib/libbsp/m68k/gen68340/startup/linkcmds
index 297579ce25..e49ec2ec39 100644
--- a/c/src/lib/libbsp/m68k/gen68340/startup/linkcmds
+++ b/c/src/lib/libbsp/m68k/gen68340/startup/linkcmds
@@ -20,7 +20,7 @@
 /*
  * Declare some sizes.
  */
-_RamBase = 0x10000000;
+_RamBase = DEFINED(_RamBase) ? _RamBase : 0x10000000;
 _RamSize = DEFINED(_RamSize) ? _RamSize : 4M;
 _HeapSize = DEFINED(_HeapSize) ? _HeapSize : 0x10000;
 _StackSize = DEFINED(_StackSize) ? _StackSize : 0x1000;
diff --git a/c/src/lib/libbsp/m68k/gen68360/startup/linkcmds b/c/src/lib/libbsp/m68k/gen68360/startup/linkcmds
index 39f4c8dbd3..fcc3b0b694 100644
--- a/c/src/lib/libbsp/m68k/gen68360/startup/linkcmds
+++ b/c/src/lib/libbsp/m68k/gen68360/startup/linkcmds
@@ -15,6 +15,8 @@
  * Declare some sizes.
  * A heap size of 0 means `use all available memory for the heap'.
  */
+_RamBase = DEFINED(_RamBase) ? _RamBase : 0x0;
+_RamSize = DEFINED(_RamSize) ? _RamSize : 64M;
 _HeapSize = DEFINED(_HeapSize) ? _HeapSize : 0x0;
 _StackSize = DEFINED(_StackSize) ? _StackSize : 0x1000;
 
diff --git a/c/src/lib/libbsp/m68k/gen68360/startup/linkcmds.bootp b/c/src/lib/libbsp/m68k/gen68360/startup/linkcmds.bootp
index 74e339717b..455d5710da 100644
--- a/c/src/lib/libbsp/m68k/gen68360/startup/linkcmds.bootp
+++ b/c/src/lib/libbsp/m68k/gen68360/startup/linkcmds.bootp
@@ -19,6 +19,8 @@
  * Declare some sizes.
  * A heap size of 0 means `use all available memory for the heap'.
  */
+_RamBase = DEFINED(_RamBase) ? _RamBase : 0x0;
+_RamSize = DEFINED(_RamSize) ? _RamSize : 64M;
 _HeapSize = DEFINED(_HeapSize) ? _HeapSize : 0x0;
 _StackSize = DEFINED(_StackSize) ? _StackSize : 0x1000;
 
diff --git a/c/src/lib/libbsp/m68k/gen68360/startup/linkcmds.prom b/c/src/lib/libbsp/m68k/gen68360/startup/linkcmds.prom
index 39ab48d096..dae2d98f47 100644
--- a/c/src/lib/libbsp/m68k/gen68360/startup/linkcmds.prom
+++ b/c/src/lib/libbsp/m68k/gen68360/startup/linkcmds.prom
@@ -19,6 +19,8 @@
  * Declare some sizes.
  * A heap size of 0 means `use all available memory for the heap'.
  */
+_RamBase = DEFINED(_RamBase) ? _RamBase : 0x0;
+_RamSize = DEFINED(_RamSize) ? _RamSize : 64M;
 _HeapSize = DEFINED(_HeapSize) ? _HeapSize : 0x0;
 _StackSize = DEFINED(_StackSize) ? _StackSize : 0x1000;
 
diff --git a/c/src/lib/libbsp/m68k/idp/startup/linkcmds b/c/src/lib/libbsp/m68k/idp/startup/linkcmds
index 9eadcedcda..556f7c1050 100644
--- a/c/src/lib/libbsp/m68k/idp/startup/linkcmds
+++ b/c/src/lib/libbsp/m68k/idp/startup/linkcmds
@@ -20,7 +20,7 @@ MEMORY
 /*
  * Declare some sizes.
  */
-_RamBase = 0x0;
+_RamBase = DEFINED(_RamBase) ? _RamBase : 0x0;
 _RamSize = DEFINED(_RamSize) ? _RamSize : 2M;
 _HeapSize = DEFINED(_HeapSize) ? _HeapSize : 0x10000;
 _StackSize = DEFINED(_StackSize) ? _StackSize : 0x1000;
diff --git a/c/src/lib/libbsp/m68k/mvme136/startup/linkcmds b/c/src/lib/libbsp/m68k/mvme136/startup/linkcmds
index 67101dcd32..8aec416acb 100644
--- a/c/src/lib/libbsp/m68k/mvme136/startup/linkcmds
+++ b/c/src/lib/libbsp/m68k/mvme136/startup/linkcmds
@@ -15,7 +15,7 @@
 /*
  * Declare some sizes.
  */
-_RamBase = 0x0;
+_RamBase = DEFINED(_RamBase) ? _RamBase : 0x0;
 _RamSize = DEFINED(_RamSize) ? _RamSize : 1M;
 _HeapSize = DEFINED(_HeapSize) ? _HeapSize : 0x10000;
 _StackSize = DEFINED(_StackSize) ? _StackSize : 0x1000;
diff --git a/c/src/lib/libbsp/m68k/mvme147/startup/linkcmds b/c/src/lib/libbsp/m68k/mvme147/startup/linkcmds
index c40af97d9d..9cb451e98b 100644
--- a/c/src/lib/libbsp/m68k/mvme147/startup/linkcmds
+++ b/c/src/lib/libbsp/m68k/mvme147/startup/linkcmds
@@ -19,7 +19,7 @@
 /*
  * Declare some sizes.
  */
-_RamBase = 0x0;
+_RamBase = DEFINED(_RamBase) ? _RamBase : 0x0;
 _RamSize = DEFINED(_RamSize) ? _RamSize : 4M;
 _HeapSize = DEFINED(_HeapSize) ? _HeapSize : 0x10000;
 _StackSize = DEFINED(_StackSize) ? _StackSize : 0x1000;
diff --git a/c/src/lib/libbsp/m68k/mvme147s/startup/linkcmds b/c/src/lib/libbsp/m68k/mvme147s/startup/linkcmds
index e752b5b33e..41d26d7508 100644
--- a/c/src/lib/libbsp/m68k/mvme147s/startup/linkcmds
+++ b/c/src/lib/libbsp/m68k/mvme147s/startup/linkcmds
@@ -19,7 +19,7 @@
 /*
  * Declare some sizes.
  */
-_RamBase = 0x0;
+_RamBase = DEFINED(_RamBase) ? _RamBase : 0x0;
 _RamSize = DEFINED(_RamSize) ? _RamSize : 4M;
 _HeapSize = DEFINED(_HeapSize) ? _HeapSize : 0x10000;
 _StackSize = DEFINED(_StackSize) ? _StackSize : 0x1000;
diff --git a/c/src/lib/libbsp/m68k/mvme162/startup/linkcmds b/c/src/lib/libbsp/m68k/mvme162/startup/linkcmds
index 8f8c639790..60a3726f67 100644
--- a/c/src/lib/libbsp/m68k/mvme162/startup/linkcmds
+++ b/c/src/lib/libbsp/m68k/mvme162/startup/linkcmds
@@ -22,7 +22,7 @@
 /*
  * Declare some sizes.
  */
-_RamBase = 0x100000;
+_RamBase = DEFINED(_RamBase) ? _RamBase : 0x100000;
 _RamSize = DEFINED(_RamSize) ? _RamSize : 1M;
 _HeapSize = DEFINED(_HeapSize) ? _HeapSize : 0x10000;
 _StackSize = DEFINED(_StackSize) ? _StackSize : 0x1000;
diff --git a/c/src/lib/libbsp/m68k/ods68302/startup/linkcmds b/c/src/lib/libbsp/m68k/ods68302/startup/linkcmds
index 3911aaed12..dc2f820414 100644
--- a/c/src/lib/libbsp/m68k/ods68302/startup/linkcmds
+++ b/c/src/lib/libbsp/m68k/ods68302/startup/linkcmds
@@ -8,7 +8,7 @@
 /*
  * Declare some sizes.
  */
-_RamBase = 0x0;
+_RamBase = DEFINED(_RamBase) ? _RamBase : 0x0;
 _RamSize = DEFINED(_RamSize) ? _RamSize : 1M;
 _HeapSize = DEFINED(_HeapSize) ? _HeapSize : 0x10000;
 _StackSize = DEFINED(_StackSize) ? _StackSize : 0x1000;