Fix to bugzilla bug 4065

Detail:
    1MB VRAM was not being correctly identified. This was due to register
corruption in r12 in the VRAM detection routines in s.ARM600. This bug has been a longstanding one introduced in Kernel 4.69 two years ago.

Admin:
    Been put through the Kev&Mike change control process (tm).

Version 5.40. Tagged as 'Kernel-5_40'

VersionASM

@@ -11,14 +11,14 @@
                         GBLS    Module_HelpVersion
                         GBLS    Module_ComponentName
                         GBLS    Module_ComponentPath
-Module_MajorVersion     SETS    "5.39"
-Module_Version          SETA    539
+Module_MajorVersion     SETS    "5.40"
+Module_Version          SETA    540
 Module_MinorVersion     SETS    ""
-Module_Date             SETS    "05 Jan 2001"
-Module_ApplicationDate2 SETS    "05-Jan-01"
-Module_ApplicationDate4 SETS    "05-Jan-2001"
+Module_Date             SETS    "02 Apr 2001"
+Module_ApplicationDate2 SETS    "02-Apr-01"
+Module_ApplicationDate4 SETS    "02-Apr-2001"
 Module_ComponentName    SETS    "Kernel"
 Module_ComponentPath    SETS    "RiscOS/Sources/Kernel"
-Module_FullVersion      SETS    "5.39"
-Module_HelpVersion      SETS    "5.39 (05 Jan 2001)"
+Module_FullVersion      SETS    "5.40"
+Module_HelpVersion      SETS    "5.40 (02 Apr 2001)"
                         END

VersionNum

-/* (5.39)
+/* (5.40)
  *
  * This file is automatically maintained by srccommit, do not edit manually.
  *
  */
-#define Module_MajorVersion_CMHG        5.39
+#define Module_MajorVersion_CMHG        5.40
 #define Module_MinorVersion_CMHG        
-#define Module_Date_CMHG                05 Jan 2001
+#define Module_Date_CMHG                02 Apr 2001
 
-#define Module_MajorVersion             "5.39"
-#define Module_Version                  539
+#define Module_MajorVersion             "5.40"
+#define Module_Version                  540
 #define Module_MinorVersion             ""
-#define Module_Date                     "05 Jan 2001"
+#define Module_Date                     "02 Apr 2001"
 
-#define Module_ApplicationDate2         "05-Jan-01"
-#define Module_ApplicationDate4         "05-Jan-2001"
+#define Module_ApplicationDate2         "02-Apr-01"
+#define Module_ApplicationDate4         "02-Apr-2001"
 
 #define Module_ComponentName            "Kernel"
 #define Module_ComponentPath            "RiscOS/Sources/Kernel"
 
-#define Module_FullVersion              "5.39"
-#define Module_HelpVersion              "5.39 (05 Jan 2001)"
+#define Module_FullVersion              "5.40"
+#define Module_HelpVersion              "5.40 (02 Apr 2001)"

s/ARM600

@@ -1548,6 +1548,7 @@ MemSizeIOMD_not810
 ; Now, we check out the VRAM.
 ; Don't bother checking for more than 2M of VRAM, because we don't know what the 1/2 SAM length is for larger sizes
 
+        MOV     r12, #IOMD_Base
         MOV     r2, #IOMD_VREFCR_VRAM_256Kx64 :OR: IOMD_VREFCR_REF_16 ; assume 2 banks of VRAM by default
         STRB    r2, [r12, #IOMD_VREFCR]