upstream/0.3.8/TODO

$Id: TODO,v 1.209 2006/02/18 21:03:09 debug Exp $

Hm. This file is in random order, and not all parts of it are up-to-date.

Algor:  PCI and ISA and LOCAL interrupts! --> wdc could start working
        Add interrupt controller in dev_algor.c.

Dyntrans:
        TOP Priority:
                x)  64-bit stuff: good generic virtual memory translation, and
                    other structures. not all 64 bits need to be used
                    (e.g. Alpha)
                x)  Delay slots!
                x)  Old MIPS -> dyntrans!
        Other stuff:
        x)  INVALIDATION should cause translations in _all_ cpus to be
            invalidated, e.g. on a write to a write-protected page
            (containing code)
        x)  Think about sharing code between CPUs of the same
            arch/bitlength/endianness (the translation caches).
            (Eg. a little-endian R4000 and a little-endian R5000 could
            share code, but not an R3000 and an R4000.)
        x)  better (meaningful) instr call statistics
        x)  Call/return hints?
        x)  16-bit encodings? (MIPS16, ARM Thumb, SH3, ...)
        x)  PPC optimizations; instr combs
        x)  Alpha
        x)  SPARC
        x)  PPC (64-bit stuff)
        x)  Lots of other stuff: see src/cpus/README_DYNTRANS
        x)  true recompilation backend? think carefully about this,
            experiment in a separate project (not in GXemul)

More generic out_of_memory error reporting, and check everywhere!
        Causes: OpenBSD has low default limits for normal users.
                Host is 32-bit? (32-bit hosts are limited to 4 GB or less
                of userspace memory.)
                You are actually low on RAM. (As trivial as this might sound,
                Unix systems usually allow processes to allocate virtual
                memory beyond the amount of RAM in the machine.)

Breakpoints: 32-bit vs 64-bit sign extension for MIPS, warnings, etc.
        Use the debugger's symbolic name stuff. (which will have to be
        extended soon to support stuff like  "2*x + symbol + y" etc. cool
        stuff)

Sprite (guest OS for DECstation emulation)
        x)  Timing problems during bootup?

The Device subsystem:
        x)  allow devices to be moved and/or changed in size (down to a
            minimum size, etc, or up to a max size)
        x)  keep track of interrupts and busses? actually, allowing any device
            to be a bus might be a nice idea
        x)  refactor various clocks/nvram/cmos into one device?

ARM:
        o)  add ID for "i80321 600MHz rev 2 (XScale core)"
        o)  make the ata controller usable for FreeBSD!
        x)  zaurus for openbsd...

PCI:
        x)  add support for address fixups
        x)  generalize the interrupt routing stuff (lines etc). this should
            be per machine? or per bus, that's better

MacPPC:
        x)  dev_zs / interrupts?
        x)  adb controller; keyboard
        x)  make OpenBSD/macppc work (PCI controller stuff)

Network layer:
        o)  DHCP (for Debian and BSD installers :-)
        o)  increase performance
        o)  don't rely on NetBSD-ish usage
        o)  Multiple networks per emulation, and let different
            NICs in machines connect to different networks.
        o)  many other issues: see src/net.c

Busses:
        o)  Redesign the entire "mainbus" concept!
        o)  Busses should be placed in a hierarchical tree!
        o)  Easily configurable interrupt routing in SMP systems.
        o)  Specific clock/bus speeds, cpu speeds etc.
        o)  Synchronization over network? or at least in dyntrans within
            one emulated machine
        o)  dev->bus: TurboChannel, PCMCIA, ADB?

Config file parser:
        o)  Refresh/rewrite it :)
        o)  Usage of any expression available through the debugger
        o)  Expressions such as "add device" would be nice to be able
            to do on the command line manually.
        o)  Allow machine() entries even if there is no emul() entry (but
            then don't allow any emul() entries at all).
        o)  Support for running debugger commands (like the -c
            command line option)

Floating point layer:
        o)  make it common enough to be used by _all_ emulation modes
        o)  non-IEEE modes (i.e. x86)?

Userland emulation:
        x)  Lots of stuff; freebsd and netbsd (and linux?) syscalls.
        x)  Dynamic linking? Hm.

Sound:
        x)  generic sound framework
        x)  add one or more sound cards as devices

Caches / memory hierarchies: (this is mostly MIPS-specific)
        o)  MIPS coproc.c: bits in config registers should reflect
            correct cache sizes for _all_ CPU types. (currently only
            implemented for R4000, R1x000, and a few others)
        o)  src/memory*.c: Implement correct cache emulation for
            all CPU types. (currently only R2000/R3000 is implemented)
            (per CPU, multiple levels should be possible,
            associativity etc!)
        o)  R2000/R3000 isn't _100%_ correct, just almost correct :)
        o)  Move the -S (fill mem with random) functionality into the
            memory.c subsystem, not machine.c or wherever it is now
        o)  ECC stuff, simulation of memory errors?  (Machine dependent)
        o)  More than 4GB of emulated RAM, when run on a 32-bit host?
            (using manual swap-out of blocks to disk, ugly)
        o)  A global command line option should be used to turn
            cache emulation on or off. When off, caches should be
            faked like they are right now. When on, caches and
            memory latencies should be emulated as correctly as
            possible.

MIPS CPU emulation:  (note: this is for the OLD mips stuff)
        o)  i386 bintrans backend: movn etc, slt[u] for
                64-bit mode, 64-bit shifts etc
        o)  Instructions:
                o)  All ISAs:
                        o)  Floating point exception handling, and
                                add more instructions.
                        o)  Finish the MIPS16 translator, and test it!
                        o)  MIPS ISA I, II, III, IV
                        o)  MIPS V (SIMD vector stuff?)
                        o)  MDMX  (MIPS Digital Media Extension)
                        o)  MIPS 3D
                        o)  MIPS MT (Multi-thread stuff) (What's this?)
                o)  Warn about mis-used bit fields (ie bits that
                    should be all zeroes, warn about if they are not)!
                    Both for coprocessor registers and for instruction
                    opcodes.
                o)  the special2 stuff is a mess right now
                o)  warn and/or cause exceptions for unimplemented
                    instructions (depending on CPU type)
        o)  R2000/R3000:
                x)  R3000 "tri-byte stores". (What's this?)
        o)  R4000 and others:
                x)  watchhi/watchlo exceptions, and other exception
                    handling details
        o)  R10000 and others:  (R12000, R14000 ?)
                x)  memory space, exceptions, ...
                x)  use cop0 framemask for tlb lookups
                    (http://techpubs.sgi.com/library/tpl/cgi-bin/getdoc.cgi/hdwr/bks/SGI_Developer/books/R10K_UM/sgi_html/t5.Ver.2.0.book_284.html)
        o)  Implement load delays?  Warnings on interlocks.
        o)  Implement all coprocessor 0 bits / functions.
                x)  coproc 0 selectors! (R4000 ?)
        o)  R4300 (nintendo64, no mmu?), R5900 (playstation2, weird
                TLB/cache? 128-bit GPRs, new instructions),
                4K (note: NOT R4000), 5K (note: NOT R5000),
                R6000 (ISA II), R8000
        o)  Multi-cpu stuff:
                +)  Interrupt routing (ie devices vs mainbus, or
                    connect each device to a fixed cpu)
                +)  SGI's NUMA architecture. Study
                        x)  Linux sources
                        x)  SGI's specs on NUMA address space
                +)  Ultrix?  NetBSD doesn't do SMP on MIPS yet :-(
                +)  Own experiments with ycx2.

File/disk/symbol handling:
        o)  Better handling of tape files
        o)  Read function argument count and types from binaries? (ELF?)
        o)  Demangle C++ names.

Debugger:
        o)  see src/debugger.c for more

Userland ABI emulation:
        o)  see src/useremul.c

Terminal/console:
        o)  allow emulated serial ports to be connected to the outside
            world in a more generic way, or even to other emulated
            machines(?)

Save state of the whole emulated machine, to be able to load it back
        in later?  (Memory, all device's states, all registers and
        so on.  Like taking a snapshot. (SimOS seems to do this,
        according to its website.))

Better framebuffer and X-windows functionality:
        o)  -Yx sometimes causes crashes.
        o)  Simple device access to framebuffer_blockcopyfill() etc,
            and text output (using the built-in fonts), for dev_fb.
        o)  CLEAN UP the ugly event code
        o)  Mouse clicks can be "missed" in the current system; this is
            not good. They should be put on a stack of some kind.
        o)  More 2D and 3D framebuffer acceleration.
        o)  Non-resizable windows?  Or choose scaledown depending
                on size (and center the image, with a black border).
        o)  Different scaledown on different windows?
        o)  Switch scaledown during runtime? (Ala CTRL-ALT-plus/minus)
        o)  Keyboard and mouse events:
                x)  Do this for more machines than just DECstation
                x)  more X11 cursor keycodes
                x)  Keys like CTRL, ALT, SHIFT do not get through
                    by themselves (these are necessary for example
                    to change the font of an xterm in X in the
                    emulator)
        o)  Generalize the framebuffer stuff by moving _ALL_ X11
                specific code to src/x11.c!

Statistics:  (this could be interesting)
        o)  Save to file and show graphics. It should be possible to
            run gxemul after a simulation to just show the graphics,
            or convert to a .ppm or .tga or similar.
        o)  memory accesses (to measure cache efficiency and
                page coloring efficiency)
        o)  nr of simultaneous ASIDs in use in the TLB, for MIPS
        o)  percentage of time spent in different "states", such as
            running userland code, kernel code, or idling (for CPUs
            that have such an instruction, or whenever the PC is
            inside a specific idle-function (address range)).
            Possible additional state (for example on R3000): caches
            disabled.
        o)  position of read/write on (SCSI) disks

1	$Id: TODO,v 1.209 2006/02/18 21:03:09 debug Exp $
2
3	Hm. This file is in random order, and not all parts of it are up-to-date.
4
5	Algor: PCI and ISA and LOCAL interrupts! --> wdc could start working
6	Add interrupt controller in dev_algor.c.
7
8	Dyntrans:
9	TOP Priority:
10	x) 64-bit stuff: good generic virtual memory translation, and
11	other structures. not all 64 bits need to be used
12	(e.g. Alpha)
13	x) Delay slots!
14	x) Old MIPS -> dyntrans!
15	Other stuff:
16	x) INVALIDATION should cause translations in _all_ cpus to be
17	invalidated, e.g. on a write to a write-protected page
18	(containing code)
19	x) Think about sharing code between CPUs of the same
20	arch/bitlength/endianness (the translation caches).
21	(Eg. a little-endian R4000 and a little-endian R5000 could
22	share code, but not an R3000 and an R4000.)
23	x) better (meaningful) instr call statistics
24	x) Call/return hints?
25	x) 16-bit encodings? (MIPS16, ARM Thumb, SH3, ...)
26	x) PPC optimizations; instr combs
27	x) Alpha
28	x) SPARC
29	x) PPC (64-bit stuff)
30	x) Lots of other stuff: see src/cpus/README_DYNTRANS
31	x) true recompilation backend? think carefully about this,
32	experiment in a separate project (not in GXemul)
33
34	More generic out_of_memory error reporting, and check everywhere!
35	Causes: OpenBSD has low default limits for normal users.
36	Host is 32-bit? (32-bit hosts are limited to 4 GB or less
37	of userspace memory.)
38	You are actually low on RAM. (As trivial as this might sound,
39	Unix systems usually allow processes to allocate virtual
40	memory beyond the amount of RAM in the machine.)
41
42	Breakpoints: 32-bit vs 64-bit sign extension for MIPS, warnings, etc.
43	Use the debugger's symbolic name stuff. (which will have to be
44	extended soon to support stuff like "2*x + symbol + y" etc. cool
45	stuff)
46
47	Sprite (guest OS for DECstation emulation)
48	x) Timing problems during bootup?
49
50	The Device subsystem:
51	x) allow devices to be moved and/or changed in size (down to a
52	minimum size, etc, or up to a max size)
53	x) keep track of interrupts and busses? actually, allowing any device
54	to be a bus might be a nice idea
55	x) refactor various clocks/nvram/cmos into one device?
56
57	ARM:
58	o) add ID for "i80321 600MHz rev 2 (XScale core)"
59	o) make the ata controller usable for FreeBSD!
60	x) zaurus for openbsd...
61
62	PCI:
63	x) add support for address fixups
64	x) generalize the interrupt routing stuff (lines etc). this should
65	be per machine? or per bus, that's better
66
67	MacPPC:
68	x) dev_zs / interrupts?
69	x) adb controller; keyboard
70	x) make OpenBSD/macppc work (PCI controller stuff)
71
72	Network layer:
73	o) DHCP (for Debian and BSD installers :-)
74	o) increase performance
75	o) don't rely on NetBSD-ish usage
76	o) Multiple networks per emulation, and let different
77	NICs in machines connect to different networks.
78	o) many other issues: see src/net.c
79
80	Busses:
81	o) Redesign the entire "mainbus" concept!
82	o) Busses should be placed in a hierarchical tree!
83	o) Easily configurable interrupt routing in SMP systems.
84	o) Specific clock/bus speeds, cpu speeds etc.
85	o) Synchronization over network? or at least in dyntrans within
86	one emulated machine
87	o) dev->bus: TurboChannel, PCMCIA, ADB?
88
89	Config file parser:
90	o) Refresh/rewrite it :)
91	o) Usage of any expression available through the debugger
92	o) Expressions such as "add device" would be nice to be able
93	to do on the command line manually.
94	o) Allow machine() entries even if there is no emul() entry (but
95	then don't allow any emul() entries at all).
96	o) Support for running debugger commands (like the -c
97	command line option)
98
99	Floating point layer:
100	o) make it common enough to be used by _all_ emulation modes
101	o) non-IEEE modes (i.e. x86)?
102
103	Userland emulation:
104	x) Lots of stuff; freebsd and netbsd (and linux?) syscalls.
105	x) Dynamic linking? Hm.
106
107	Sound:
108	x) generic sound framework
109	x) add one or more sound cards as devices
110
111	Caches / memory hierarchies: (this is mostly MIPS-specific)
112	o) MIPS coproc.c: bits in config registers should reflect
113	correct cache sizes for _all_ CPU types. (currently only
114	implemented for R4000, R1x000, and a few others)
115	o) src/memory*.c: Implement correct cache emulation for
116	all CPU types. (currently only R2000/R3000 is implemented)
117	(per CPU, multiple levels should be possible,
118	associativity etc!)
119	o) R2000/R3000 isn't _100%_ correct, just almost correct :)
120	o) Move the -S (fill mem with random) functionality into the
121	memory.c subsystem, not machine.c or wherever it is now
122	o) ECC stuff, simulation of memory errors? (Machine dependent)
123	o) More than 4GB of emulated RAM, when run on a 32-bit host?
124	(using manual swap-out of blocks to disk, ugly)
125	o) A global command line option should be used to turn
126	cache emulation on or off. When off, caches should be
127	faked like they are right now. When on, caches and
128	memory latencies should be emulated as correctly as
129	possible.
130
131	MIPS CPU emulation: (note: this is for the OLD mips stuff)
132	o) i386 bintrans backend: movn etc, slt[u] for
133	64-bit mode, 64-bit shifts etc
134	o) Instructions:
135	o) All ISAs:
136	o) Floating point exception handling, and
137	add more instructions.
138	o) Finish the MIPS16 translator, and test it!
139	o) MIPS ISA I, II, III, IV
140	o) MIPS V (SIMD vector stuff?)
141	o) MDMX (MIPS Digital Media Extension)
142	o) MIPS 3D
143	o) MIPS MT (Multi-thread stuff) (What's this?)
144	o) Warn about mis-used bit fields (ie bits that
145	should be all zeroes, warn about if they are not)!
146	Both for coprocessor registers and for instruction
147	opcodes.
148	o) the special2 stuff is a mess right now
149	o) warn and/or cause exceptions for unimplemented
150	instructions (depending on CPU type)
151	o) R2000/R3000:
152	x) R3000 "tri-byte stores". (What's this?)
153	o) R4000 and others:
154	x) watchhi/watchlo exceptions, and other exception
155	handling details
156	o) R10000 and others: (R12000, R14000 ?)
157	x) memory space, exceptions, ...
158	x) use cop0 framemask for tlb lookups
159	(http://techpubs.sgi.com/library/tpl/cgi-bin/getdoc.cgi/hdwr/bks/SGI_Developer/books/R10K_UM/sgi_html/t5.Ver.2.0.book_284.html)
160	o) Implement load delays? Warnings on interlocks.
161	o) Implement all coprocessor 0 bits / functions.
162	x) coproc 0 selectors! (R4000 ?)
163	o) R4300 (nintendo64, no mmu?), R5900 (playstation2, weird
164	TLB/cache? 128-bit GPRs, new instructions),
165	4K (note: NOT R4000), 5K (note: NOT R5000),
166	R6000 (ISA II), R8000
167	o) Multi-cpu stuff:
168	+) Interrupt routing (ie devices vs mainbus, or
169	connect each device to a fixed cpu)
170	+) SGI's NUMA architecture. Study
171	x) Linux sources
172	x) SGI's specs on NUMA address space
173	+) Ultrix? NetBSD doesn't do SMP on MIPS yet :-(
174	+) Own experiments with ycx2.
175
176	File/disk/symbol handling:
177	o) Better handling of tape files
178	o) Read function argument count and types from binaries? (ELF?)
179	o) Demangle C++ names.
180
181	Debugger:
182	o) see src/debugger.c for more
183
184	Userland ABI emulation:
185	o) see src/useremul.c
186
187	Terminal/console:
188	o) allow emulated serial ports to be connected to the outside
189	world in a more generic way, or even to other emulated
190	machines(?)
191
192	Save state of the whole emulated machine, to be able to load it back
193	in later? (Memory, all device's states, all registers and
194	so on. Like taking a snapshot. (SimOS seems to do this,
195	according to its website.))
196
197	Better framebuffer and X-windows functionality:
198	o) -Yx sometimes causes crashes.
199	o) Simple device access to framebuffer_blockcopyfill() etc,
200	and text output (using the built-in fonts), for dev_fb.
201	o) CLEAN UP the ugly event code
202	o) Mouse clicks can be "missed" in the current system; this is
203	not good. They should be put on a stack of some kind.
204	o) More 2D and 3D framebuffer acceleration.
205	o) Non-resizable windows? Or choose scaledown depending
206	on size (and center the image, with a black border).
207	o) Different scaledown on different windows?
208	o) Switch scaledown during runtime? (Ala CTRL-ALT-plus/minus)
209	o) Keyboard and mouse events:
210	x) Do this for more machines than just DECstation
211	x) more X11 cursor keycodes
212	x) Keys like CTRL, ALT, SHIFT do not get through
213	by themselves (these are necessary for example
214	to change the font of an xterm in X in the
215	emulator)
216	o) Generalize the framebuffer stuff by moving _ALL_ X11
217	specific code to src/x11.c!
218
219	Statistics: (this could be interesting)
220	o) Save to file and show graphics. It should be possible to
221	run gxemul after a simulation to just show the graphics,
222	or convert to a .ppm or .tga or similar.
223	o) memory accesses (to measure cache efficiency and
224	page coloring efficiency)
225	o) nr of simultaneous ASIDs in use in the TLB, for MIPS
226	o) percentage of time spent in different "states", such as
227	running userland code, kernel code, or idling (for CPUs
228	that have such an instruction, or whenever the PC is
229	inside a specific idle-function (address range)).
230	Possible additional state (for example on R3000): caches
231	disabled.
232	o) position of read/write on (SCSI) disks
233