Module Name: src
Committed By: dholland
Date: Thu Jun 16 01:33:35 UTC 2016
Added Files:
src/sys/arch/mips: README.models
Log Message:
Notes on MIPS models and architecture levels and their properties and
handling in NetBSD.
This is very preliminary so far, because I'm trying to get citations
from documentation for everything.
Please add stuff.
To generate a diff of this commit:
cvs rdiff -u -r0 -r1.1 src/sys/arch/mips/README.models
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Added files:
Index: src/sys/arch/mips/README.models
diff -u /dev/null src/sys/arch/mips/README.models:1.1
--- /dev/null Thu Jun 16 01:33:35 2016
+++ src/sys/arch/mips/README.models Thu Jun 16 01:33:35 2016
@@ -0,0 +1,267 @@
+# $NetBSD: README.models,v 1.1 2016/06/16 01:33:35 dholland Exp $
+
+MIPS models and architecture levels
+-----------------------------------
+
+Since this is a complex and confusing topic and there's a shortage of
+information (especially, a shortage of reliable information), I'm
+creating this document as a reference for people doing MIPS stuff on
+NetBSD (and elsewhere).
+
+Citations appear in []. With luck all important facts have citations.
+
+
+------------------------------------------------------------
+1. Architecture levels.
+
+These architecture levels exist:
+
+ 32-bit 64-bit
+
+ MIPS-I
+ MIPS-II
+ MIPS-III
+ MIPS-IV
+ MIPS-V
+ MIPS32 MIPS64
+ MIPS32r2 MIPS64r2
+ MIPS32r3 MIPS64r3
+ MIPS32r4 MIPS64r4
+ MIPS32r5 MIPS64r5
+ MIPS32r6 MIPS64r6
+
+Note that while MIPS32 is a 32-bit subset of MIPS64, each
+corresponding pair of MIPS32rN and MIPS64rN are comparable in age and
+properties. Later revisions (further down the list) are mostly subsets
+of earlier revisions, although some exceptions exist.
+
+
+------------------------------------------------------------
+2. CPU models.
+
+For vintage MIPS these are the standard models as of fall 1996 [idt96
+A-198] and the corresponding architecture levels. (There were many
+additional models put out by licensees or by the MIPS company itself,
+which have model numbers with fewer zeros.)
+
+ R2000 MIPS-I (32-bit) [idt96 1-5]
+ R3000 MIPS-I (32-bit) [idt96 1-5]
+ R4000 MIPS-III (64-bit) [idt96 A-197]
+ R4200 MIPS-III (64-bit) [idt96 A-197]
+ R4300 MIPS-III (64-bit) [idt96 A-197]
+ R4400 MIPS-III (64-bit) [idt96 A-197]
+ R4600 MIPS-III (64-bit) [idt96 A-197]
+ R5000 MIPS-IV (64-bit) [idt96 1-5]
+ R6000 MIPS-II ??
+ R8000 MIPS-IV (64-bit) [idt96 1-5]
+ R10000 MIPS-IV (64-bit) [idt96 1-5]
+
+For later models than this I currently have no information.
+
+
+------------------------------------------------------------
+3. CPU models present in various systems.
+
+These are the CPU models found in various systems NetBSD does and
+doesn't support. This table also notes endianness; MIPS chips are
+bi-endian but are wired up one way or the other on motherboards.
+
+ algor (little-endian [buildsh])
+ Algorithmics P-4000i ??
+ Algorithmics P-4032 ??
+ Algorithmics P-5064 ??
+ Algorithmics P-6032 ??
+ arc (little-endian [buildsh])
+ Acer PICA ??
+ MIPS Magnum 4000 ??
+ NEC Image RISCstation ??
+ NEC Express RISCserver ??
+ NEC RISCserver 2200 ??
+ NEC RISCstation 2200 ??
+ NEC RISCstation 2250 ??
+ NEC Express5800/230 R4400 PCI presumably R4400 (MIPS-III)
+ NEC Express5800/240 R4400 EISA presumably R4400 (MIPS-III)
+ DeskStation Tyne ??
+ cobalt (little-endian [buildsh])
+ Qube ... ?? ??
+ RaQ ... ?? ??
+ emips (big-endian [buildsh])
+ ... ?? ??
+ (see http://research.microsoft.com/en-us/projects/emips/ )
+ evbmips
+ ... ?? ?? (various-endian)
+ ews4800mips (big-endian [buildsh])
+ EWS4800/350 ??
+ EWS4800/350F ??
+ EWS4800/360AD ??
+ EWS4800/360ADII ??
+ EWS4800/360SX ??
+ EWS4800/360EX ??
+ EWS4800/360 ??
+ ... ?? ??
+ hpcmips (big-endian [buildsh])
+ see http://wiki.netbsd.org/ports/hpcmips/processor_comparison/
+ mipsco (big-endian [buildsh])
+ Mips Magnum 3000 Workstation ??
+ Mips 3230 Server ??
+ Bull DPX/Prostation M-20 ??
+ newsmips (big-endian [buildsh])
+ NWS-3470D R3000 (MIPS-I) [portpage]
+ NWS-3410 R3000 (MIPS-I) [portpage]
+ NWS-3460 R3000 (MIPS-I) [portpage]
+ NWS-3710 R3000 (MIPS-I) [portpage]
+ NWS-3720 R3000 (MIPS-I) [portpage]
+ NWS-3800 series ??
+ NWS-4000 series R4600 (MIPS-III) [portpage]
+ NWS-5000 R4[04]00 (MIPS-III) [portpage]
+ playstation2 (little-endian [buildsh])
+ playstation2 ??
+ pmax (little-endian [buildsh])
+ DECstation/system 2100 and 3100 R2000 (MIPS-I) [portpage]
+ DECsystem 5100 R3000 (MIPS-I) [portpage]
+ Personal DECstation 5000/20, /25, /33 R3000 (MIPS-I) [portpage]
+ Personal DECstation 5000/50 R4000 (MIPS-III) [portpage]
+ DECstation/system 5000/120, /125, /133 R3000 (MIPS-I) [portpage]
+ DECstation/system 5000/150 R4000 (MIPS-III) [portpage]
+ DECstation/system 5000/200 R3000 (MIPS-I) [portpage]
+ DECstation/system 5000/240 R3000 (MIPS-I) [portpage]
+ DECstation/system 5000/260 R4400 (MIPS-III) [portpage]
+ DECsystem 5900 R3000 (MIPS-I) [portpage]
+ DECsystem 5900-260 R4400 (MIPS-III) [portpage]
+ DECsystem 5500 R3000 (MIPS-I) [portpage]
+ sbmips
+ BCM91250A (Swarm) evaluation board Broadcomm BCM1250 [portpage]
+ sgimips (big-endian [buildsh])
+ 4D/20 ??
+ 4D/25 ??
+ Indigo R3000 (MIPS-I) [portpage]
+ Indigo (R4x00) R4?00 (MIPS-III) [portpage]
+ 4D/30 ??
+ 4D/35 ??
+ Indigo2 (R4x00) R4?00 (MIPS-III) [portpage]
+ Challenge M ??
+ Indy (R4x00) R4?00 (MIPS-III) [portpage]
+ Indy (R5000) R5000 (??) [portpage]
+ Challenge S (R4x00) R4?00 (MIPS-III) [portpage]
+ Challenge S (R5000) R5000 (??) [portpage]
+ R10000 Power Indigo2 R10000 (MIPS-IV) [portpage]
+ Octane ??
+ O2 (R5000) R5000 (??) [portpage]
+ O2 (RM5200) RM5200 (??) [portpage]
+ O2 (R10000) R10000 (MIPS-IV) [portpage]
+ O2 (R12000) R12000 (??) [portpage]
+ Fuel ??
+ Tezro ??
+ ... ??
+
+
+------------------------------------------------------------
+4. FPU properties
+
+TBD... this is complex and messy (XXX / ??)
+
+
+------------------------------------------------------------
+5. Exception handling properties
+
+TBD... (XXX / ??)
+
+
+------------------------------------------------------------
+6. MMU properties
+
+TBD... (XXX / ??)
+
+
+------------------------------------------------------------
+7. Cache properties
+
+TBD... (XXX / ??)
+
+
+------------------------------------------------------------
+8. Instruction ordering properties and hazards
+
+TBD... (XXX / ??)
+
+In the absence of the SYNC instruction before MIPS-II [idt96 A-172,
+mips32insn 215], apparently on a R3000 you can force pending memory
+writes to complete by doing an uncached read. [idt96 11-13]
+
+Apparently also on some models but not others the state of the write
+buffer is wired to the coprocessor 0 condition bit and you can also do
+this by using the otherwise useless bc0f instruction (branch on
+coprocessor 0 false) to loop. [no citation, I found this in passing
+the other day with Google while looking for something else]
+
+
+------------------------------------------------------------
+9. Pipeline hazards
+
+TBD... (XXX / ??)
+
+On MIPS-I a load instruction requires an explicit one-cycle wait
+before using the result. This restriction was lifted in MIPS-II,
+with the addition of an interlock in the pipeline. [idt96 A-2]
+
+A multiply should not be started within two cycles of a MFHI or MFLO
+instruction, as an interrupt that requires restarting the MFHI or MFLO
+might (will) get the result from the subsequent multiply. At least on
+MIPS-I. [idt96 2-4] I guess this is true for divides as well.
+
+
+------------------------------------------------------------
+10. Coprocessor 0 hazards
+
+TBD... (XXX / ??)
+
+
+----------------------------------------------------------------------
+11. Deprecated/removed material.
+
+When the exception handling model was changed for MIPS-III
+(introducing the ERET instruction) the RFE instruction supporting the
+old model was removed. [idt96 A-134]
+
+Coprocessor 3 (that is, the ability to have a third coprocessor, which
+had never been used for anything) was removed in MIPS-III [idt96 A-197].
+
+The branch likely instructions (e.g. BEQL) were added in MIPS-II
+[mips32insn 56] and deprecated not long after, at least by MIPS32
+[mips32insn 57] and may by now have finally been removed.
+
+... ??
+
+------------------------------------------------------------
+12. Conditional compilation in NetBSD
+
+TBD... (XXX / ??)
+
+
+------------------------------------------------------------
+References:
+
+[buildsh] The MACHINE/MACHINE_ARCH architecture table in NetBSD
+ build.sh.
+
+[idt96] "IDT MIPS Microprocessor Family Software Reference Manual",
+ Integrated Device Technology, Version 2.0, dated October 1996.
+
+[mips32intro] "MIPS32(TM) Architecture For Programmers Volume I:
+ Introduction to the MIPS32(TM) Architecture", MIPS
+ Technologies, Document Number MD00082, Revision 0.95, dated
+ March 2001. This was apparently an external review version or
+ something and has been available on the Internet; the final
+ version, and later revisions, never were. (AFAIK)
+
+[mips32insn] "MIPS32(TM) Architecture For Programmers Volume II: The
+ MIPS32(TM) Instruction Set", MIPS Technologies, Document Number
+ MD00086, Revision 0.95, March 12, 2001. Ditto.
+
+[mips32priv] "MIPS32(TM) Architecture For Programmers Volume III: The
+ MIPS32(TM) Privileged Resource Architecture", Document Number
+ MD00090, Revision 0.95, dated March 2001. Ditto.
+
+[portpage] The port page for this NetBSD port on wiki.netbsd.org, or a
+ subpage. Ideally these references should be replaced with
+ something less self-referential.
