Re: [PATCH 1/1] Changes for 68000 code integration.

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On Fri, Apr 27, 2012 at 12:08:37AM +0100, Luis Alves wrote:
diff --git a/arch/m68k/Kconfig.cpu b/arch/m68k/Kconfig.cpu
index 8a9c767..2abac0f 100644
--- a/arch/m68k/Kconfig.cpu
+++ b/arch/m68k/Kconfig.cpu
@@ -32,26 +32,33 @@ endchoice
 
 if M68KCLASSIC
 
-config M68000
+
+config M68XXX
 	bool
 	select CPU_HAS_NO_BITFIELDS
 	select CPU_HAS_NO_MULDIV64
 	select GENERIC_CSUM
 	help
-	  The Freescale (was Motorola) 68000 CPU is the first generation of
-	  the well known M68K family of processors. The CPU core as well as
-	  being available as a stand alone CPU was also used in many
-	  System-On-Chip devices (eg 68328, 68302, etc). It does not contain
-	  a paging MMU.
+	  Common features for the first generation of M68K CPUs. It
+	  includes the original MC68000 and CPU32 core.
+
 
 config MCPU32
 	bool
-	select CPU_HAS_NO_BITFIELDS
+	select M68XXX
 	help
 	  The Freescale (was then Motorola) CPU32 is a CPU core that is
 	  based on the 68020 processor. For the most part it is used in
 	  System-On-Chip parts, and does not contain a paging MMU.

I believe this misrepresents the CPU32 feature set. According to the old
paper copy I have of the Motorola CPU32 reference manual, the only
unimplemented instructions relative to the 68020 are these:

1) Bit field instructions
2) Module call/return
3) RMW instructions (CAS/CAS2)
4) Coprocessor instructions
5) BCD instructions

The 64 bit MUL and DIV variants are explicitly listed in the instruction set.

The CPU32 is also missing some (but not all) of the addressing modes
which were added with the 68020.

I haven't worked with any of these chips in a long time, but the CPU32
is quite a bit newer and more complicated than a 68000 or 68010. I
did a project based on a 68332 about 15 years ago and still have all
the printed reference manuals for that particular chip.

	Brad Boyer
	flar@xxxxxxxxxxxxx

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