/[gxemul]/trunk/TODO
This is repository of my old source code which isn't updated any more. Go to git.rot13.org for current projects!
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revision 10 by dpavlin, Mon Oct 8 16:18:27 2007 UTC revision 34 by dpavlin, Mon Oct 8 16:21:17 2007 UTC
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1  $Id: TODO,v 1.139 2005/06/23 06:55:43 debug Exp $  $Id: TODO,v 1.453 2007/02/19 01:34:42 debug Exp $
2    
3  Here's a short list of what I have left to do on GXemul. This file is a mess.  -------------------------------------------------------------------------------
 Order is random. Don't trust it to be up-to-date.  
4    
5          Caches / memory hierarchies: (this is mostly MIPS-specific)  Fix after the 0.4.4 release:
6                  o)  MIPS coproc.c: bits in config registers should reflect          Fix the PowerPC DECR interrupt speed!
7                      correct cache sizes for _all_ CPU types. (currently only  
8                      implemented for R4000, R1x000, and a few others)  -------------------------------------------------------------------------------
9                  o)  src/memory*.c: Implement correct cache emulation for  
10                      all CPU types. (currently only R2000/R3000 is implemented)  Possible (relatively large) work packages to concentrate on in the future:
11                      (per CPU, multiple levels should be possible,  
12                      associativity etc!)    x)  SMP:
13                  o)  R2000/R3000 isn't _100%_ correct, just almost correct :)          Get SMP working again. It is pretty much broken since I started
14                  o)  Move the -S (fill mem with random) functionality into the          the conversion from the old bintrans system to the new dyntrans system.
15                      memory.c subsystem, not machine.c or wherever it is now          Add better Test machine demos for SMP in the demos directory.
16                  o)  ECC stuff, simulation of memory errors?  (Machine dependant)  
17                  o)  More than 4GB of emulated RAM, when run on a 32-bit host?    x)  Network:
18                      (using manual swap-out of blocks to disk, ugly)          Redesign of the networking subsystem, at least the NAT translation
19                  o)  A global command line option should be used to turn          part. The current way of allowing raw ethernet frames to be
20                      cache emulation on or off. When off, caches should be          transfered to/from the emulator via UDP should probably be extended
21                      faked like they are right now. When on, caches and          to allow the frames to be transmitted other ways as well.
22                      memory latencies should be emulated as correctly as          Also adding support for connecting ttys (either to xterms, or to
23                      possible.          pipes/sockets etc, or even to PPP->NAT or SLIP->NAT :-).
24    
25          Network layer:    x)  PCI:
26                  o)  Multiple networks per emulation, and let different          Pretty much everything related to runtime configuration, device
27                      NICs in machines connect to different networks.          slots, interrupts, whatever. The current code is very hardcoded
28                  o)  many other issues: see src/net.c          and ugly.
29    
30          CPU emulation:    x)  Debugging:
31                  o)  Binary translation:          Think more about SMP debugging, etc. Right now, the
32                          +)  use an Intermediate Representation!          debugger is a mess. Also, a better connection to GDB would be
33                          +)  recursive translation?          very nice to have.
34                          +)  basic blocks instead of one-instruction? :)  
35                          +)  on Alpha: don't assume pca56-like byte load/store?    x)  Userland emulation:
36                          +)  write backends for UltraSparc and MIPS          Primary goals would be NetBSD and Linux syscall emulation.
37                          +)  see src/bintrans.c for more info  
38                  o)  Dynamic-but-not-binary translation?  And of course, there are _LOTS_ of minor TODOs spread out throughout
39                  o)  All the non-MIPS modes need a bit of work.  the source code, which must be fixed sooner or later.
40    
41          MIPS CPU emulation:  -------------------------------------------------------------------------------
42                  o)  Instructions:  
43                          o)  Regression tests (see tests/README for more info):  Some other things, in random order, that I'd like to fix: (Some items in
44                                  o)  Floating point exception handling, and  this list are probably out-to-date by now.)
45                                          add more instructions.  
46                                  o)  Finish the MIPS16 translator, and test it!  Dyntrans:
47                                  o)  MIPS ISA I, II, III, IV          x)  Instruction combination collisions? How to avoid easily...
48                                  o)  MIPS V (SIMD vector stuff?)          x)  Think about how to do both SHmedia and SHcompact in a reasonable
49                                  o)  MDMX  (MIPS Digital Media Extension)              way! (Or AMD64 long/protected/real, for that matter.)
50                                  o)  MIPS 3D          x)  68K emulation; think about how to do variable instruction
51                                  o)  MIPS MT (Multi-thread stuff) (What's this?)              lengths across page boundaries.
52                          o)  Warn about mis-used bit fields (ie bits that          x)  Dyntrans with valgrind-inspired memory checker. (In memory_rw,
53                              should be all zeroes, warn about if they are not)!              it would be reasonably simple to add; in each individual fast
54                              Both for coprocessor registers and for instruction              load/store routine = a lot more work, and it would become
55                              opcodes.              kludgy very fast.)
56                          o)  the special2 stuff is a mess right now          x)  Dyntrans with SMP... lots of work to be done here.
57                          o)  warn and/or cause exceptions for unimplemented          x)  Dyntrans with cache emulation... lots of work here as well.
58                              instructions (depending on CPU type)          o)  dev_mp doesn't work well with dyntrans yet
59                  o)  R2000/R3000:          o)  In general, IPIs, CAS, LL/SC etc must be made to work with dyntrans
60                          x)  R3000 "tri-byte stores". (What's this?)          x)  Redesign/rethink the delay slot mechanism used for e.g. MIPS,
61                  o)  R4000 and others:                  so that it caches a translation (that is, an instruction
62                          x)  watchhi/watchlo exceptions, and other exception                  word and the instr_call it was translated to the last
63                              handling details                  time), so that it doesn't need to do slow
64                  o)  R10000 and others:  (R12000, R14000 ?)                  to_be_translated for each end of page?
65                          x)  memory space, exceptions, ...          x)  Program Counter statistics:
66                          x)  use cop0 framemask for tlb lookups                  Per machine? What about SMP? All data to the same file?
67                              (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)                  A debugger command should be possible to use to enable/
68                  o)  Implement load delays?  Warnings on interlocks.                  disable statistics gathering.
69                  o)  Implement all coprocessor 0 bits / functions.                  Configuration file option!
70                          x)  coproc 0 selectors! (R4000 ?)          x)  Breakpoints:
71                  o)  R4300 (nintendo64, no mmu?), R5900 (playstation2, weird                  o) Physical vs virtual addresses!
72                          TLB/cache? 128-bit GPRs, new instructions),                  o) 32-bit vs 64-bit sign extension for MIPS, and others?
73                          4K (note: NOT R4000), 5K (note: NOT R5000),          x)  INVALIDATION should cause translations in _all_ cpus to be
74                          R6000 (ISA II), R8000              invalidated, e.g. on a write to a write-protected page
75                  o)  Multi-cpu stuff:              (containing code)
76                          +)  SGI's NUMA architecture. Study          x)  16-bit encodings? (MIPS16, ARM Thumb, 32-bit SH on SH64)
77                                  x)  Linux sources          x)  Lots of other stuff: see src/cpus/README_DYNTRANS
78                                  x)  SGI's specs on NUMA address space          x)  true recompilation backend? think carefully about this.
79                          +)  Ultrix?  NetBSD doesn't do SMP on MIPS yet :-(                  o)  abstract syntax for emitting opcopdes
80                          +)  Own experiments with ycx2.                  o)  convert into native code only after an entire
81                            block has been translated? probably best.
82          Emulation of specific machines and devices:                  o)  x86/amd64 code generator can be very similar... perhaps
83                  o)  Use same clock for all emulations and machines.                  o)  branches to already translated code blocks can
84                  o)  Clean up the device stuff (registering of devices etc)                          link the blocks together
85                  o)  Various SCSI and IDE controllers                  o)  load/store are the most important.
86                  o)  PS/2-style keyboard controller (for several machines)  
87                  o)  Generic busses;  Simple Valgrind-like checks?
88                          x)  PCI:  i/o and interrupts          o)  Mark every address with bits which tell whether or not the address
89                          x)  QBus-22 (DECsystem 5500, 5400?)              has been written to.
90                  o)  DECstations (pmax):          o)  What should happen when programs are loaded?  Text/data, bss (zero
91                          x)  ioasic              filled). But stack space and heap is uninitialized.
92                          x)  framebuffers:          o)  Uninitialized local variables:
93                                  +)  better cursor support, overlays?,                  A load from a place on the stack which has not previously
94                                  +)  2D/3D acceleration, PX[G]                  been stored to => warning. Increasing the stack pointer using
95                          x)  status words / control words, make this more                  any available means should reset the memory to uninitialized.
96                                  portable/cleaner          o)  If calls to malloc() and free() can be intercepted:
97                          x)  scsi controller(s): sii, DMA for asc                  o)  Access to a memory area after free() => warning.
98                          x)  serial controllers: ssc, scc (and more work on dc?)                  o)  Memory returned by malloc() is marked as not-initialized.
99                          x)  nvram on decstation 5000/125:  when using X11,                  o)  Non-passive, but good to have: Change the argument
100                                  set console=g or similar                      given to malloc, to return a slightly larger memory
101                          x)  DECstation 5840? "xbi-based SMP"                      area, i.e.  margin_before + size + margin_after,
102                  o)  SGI and ARC machines (sgimips, arc):                      and return the pointer  + margin_before.
103                          x)  IP32 ("O2"): (Lots of stuff)                      Any access to the margin_before or _after space results
104                                  +)  mec (ethernet)                      in warnings. (free() must be modified to free the
105                                  +)  pci                      actually allocated address.)
106                                  +)  ahc (scsi)  
107                                  +)  ps2 kbd  MIPS:
108                                  +)  memory controller          o)  Nicer MIPS status bits in register dumps.
109                                  +)  framebuffer/graphics          o)  Alignment exceptions.
110                                  +)  caches          o)  Floating point exception correctness.
111                          x)  more ARCBIOS stuff          o)  Fix this? Triggered by NetBSD/sgimips? Hm:
112                          x)  Memory/interrupt controllers                  to_be_translated(): TODO: unimplemented instruction:
113                          x)  IP30 (Linux with graphics support?)                  000000000065102c: 00200800 (d)  rot_00  at,zr,0
114                          x)  SMP / NUMA?  (SGI and various ARC machines)          o)  Some more work on opcodes.
115                  o)  Playstation 2:                  x) MIPS64 revision 2.
116                          Hardware:  OHCI usb controller, keyboard, ...                          o)  Find out which actual CPUs implement the rev2 ISA!
117                  o)  Less interesting platforms:                          o)  DROTR32 and similar MIPS64 rev 2 instructions,
118                          o)  newsmips:                              which have a rotation bit which differs from
119                                  o)  NetBSD/newsmips, get it to detect a "real"                              previous ISAs.
120                                      model, right now everything is 100% bogus                          o)  EI and DI instructions for MIPS64/32 rev 2.
121                          o)  mipsco? (NetBSD)                              NOTE: These are _NOT_ the same as for R5900!
122                          o)  wgrisc? (big endian R3000, in OpenBSD's attic)                  x) _MAYBE_ TX79 and R5900 actually differ in their
123                          o)  other embedded / evaluation MIPS boards                     opcodes? Check this carefully!
124                          o)  Playstation 1? R3000A. Weird hardware?          o)  Dyntrans: Count register updates are probably not 100% correct yet.
125                                  No FPU, but something as coproc 2.          o)  Refactor code for performance and readability/maintainability.
126                          o)  Nintendo 64, http://www.nintendo.com/systems/n64/n64_specs.jsp          o)  (Re)implement 128-bit loads/stores for R5900.
127                                  (R4300, 4MB RAM, really weird memory map)          o)  R4000 and others:
128                    x)  watchhi/watchlo exceptions, and other exception
129          File/disk handling:                      handling details
130                  o)  Read function argument count and types from binaries? (ELF?)          o)  R10000 and others:  (R12000, R14000 ?)
131                  o)  Better handling of tape files                  x)  The code before the line
132                            /*  reg[COP0_PAGEMASK] = cpu->cd.mips.coproc[0]->tlbs[0].mask & PAGEMASK_MASK;  */
133          Userland ABI emulation:                      in cpu_mips.c is not correct for R10000 according to
134                  o)  see src/useremul.c                      Lemote's Godson patches for GXemul. TODO: Go through all
135                        register definitions according to http://techpubs.sgi.com/library/tpl/cgi-bin/getdoc.cgi/hdwr/bks/SGI_Developer/books/R10K_UM/sgi_html/t5.Ver.2.0.book_263.html#HEADING334
136          Terminal based interactive debugger:                      and make sure everything works with R10000.
137                  o)  see src/debugger.c                      Then test with OpenBSD/sgi?
138                    x)  memory space, exceptions, ...
139          Terminal/console stuff:                  x)  use cop0 framemask for tlb lookups
140                  o)  allow emulated serial ports to be connected to the outside                      (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)
141                      world in a more generic way, or even to other emulated  
142                      machines(!)  SuperH:
143            x)  SH4 interrupt controller:
144          Regression tests:  (Should be totally rewritten.)                  x)  Implement correct priorities of interrupts
145                  o)  see tests/          x)  SH4 DMA (0xffa00000)
146            x)  SH4 UBC (0xff200000)
147          Save state of the whole emulated machine, to be able to load it back          x)  Store queues can copy 32 bytes at a time, there's no need to
148                  in later?  (Memory, all device's states, all registers and              copy individual 32-bit words. (Performance improvement.)
149                  so on.  Like taking a snapshot. (SimOS seems to do this,          x)  SH4 BSC (Bus State Controller)
150                  according to its website.))          x)  SH4 RTC: Read the host's clock.
151            x)  SH4 SCIF: Serial _interrupts_
152          Better X-windows functionality:          x)  Instruction tracing should include symbols for branch targets,
153                  o)  CLEAN UP the ugly event code              and so on, to make the output more human readable.
154                  o)  Mouse clicks can be "missed" in the current system; this is          x)  NetBSD/evbsh3, dreamcast, mmeye, hpcsh! Linux?
155                      not good. They should be put on a stack of some kind.          x)  Replace pc-relative loads with immediate load, if within the
156                  o)  More 2D and 3D framebuffer acceleration.              same page. (Similar to the same optimization for ARM.)
157                  o)  Non-resizable windows?  Or choose scaledown depending          x)  Floating point speed!
158                          on size (and center the image, with a black border).          x)  Floating point exception correctness.
159                  o)  Different scaledown on different windows?          x)  Think carefully about how to implement SH5/SH64 (for evbsh5).
160                  o)  Switch scaledown during runtime? (Ala CTRL-ALT-plus/minus)  
161                  o)  Keyboard and mouse events:  Dreamcast:
162                          x)  Do this for more machines than just DECstation          x)  G2 DMA
163                          x)  more X11 cursor keycodes          x)  LAN adapter (dev_mb8696x.c).  NetBSD root-on-nfs.
164                          x)  Keys like CTRL, ALT, SHIFT do not get through          x)  PVR:  Lots of stuff. See dev_pvr.c.
165                              by themselves (these are necessary for example          x)  GDROM
166                              to change the font of an xterm in X in the          x)  Modem
167                              emulator)          x)  PCI bridge/bus?
168                  o)  Generalize the framebuffer stuff by moving _ALL_ X11          x)  Maple bus:
169                          specific code to src/x11.c!                  x)  Correct controller input
170                    x)  Mouse input
171          Statistics:  (this could be interesting)          x)  Software emulation of BIOS calls:
172                  o)  Save to file and show graphics. It should be possible to                  x)  GD-ROM emulation: Use the GDROM device.
173                      run gxemul after a simulation to just show the graphics,                  x)  Use the VGA font as a fake ROM font. (Better than
174                      or convert to a .ppm or .tga or similar.                      nothing.)
175                  o)  memory accesses (to measure cache efficiency and          x)  Linux/dreamcast? (The gentoo kernel currently crashes.)
176                          page coloring efficiency)          x)  Make as many as possible of the KOS examples run!
177                  o)  nr of simultaneous ASIDs in use in the TLB, for MIPS          x)  More homebrew demos/games.
178                  o)  percentage of time spent in different "states", such as          x)  SPU: Sound emulation (ARM cpu).
179                      running userland code, kernel code, or idling (for CPUs          x)  VME processor emulation? "(Sanyo LC8670 "Potato")" according to
180                      that have such an instruction, or whenever the PC is              Wikipedia, LC86K87 according to Comstedt's page. See
181                      inside a specific idle-function (address range)).              http://www.maushammer.com/vmu.html for a good description of
182                      Possible additional state (for example on R3000): caches              the differences between LC86104C and the one used in the VME.
183                      disabled.  
184                  o)  position of read/write on (SCSI) disks  Transputer:
185            x)  Implement support for Helios binaries.
186            x)  Stack and register contents at startup?
187            x)  Figure out how to boot an entire Helios distribution.
188            x)  Implement all instructions. :)
189    
190    RCA1802/RCA1805, CHIP8:
191            x)  CHIP8 -> RCA180x conversion
192                    x)  Think about how to do dual-mode, variable-instr-length
193                        ISAs, and switch between modes.
194                    x)  1805 "extended" opcode -> trigger CHIP8 emulation?
195                            That is, all calls 0NNN could point to 0x68 opcodes,
196                            which, if running on a 1802 in CHIP8-emulation-mode,
197                            would be manually interpreted.
198                    x)  Better solution:
199                            CHIP8 calls to 00xx => handle at high level,
200                                  calls to 0xxx in general = call 180X machine code
201                                    (0000 = reboot?)
202            x)  1802 info: http://www.nyx.net/~lturner/public_html/Cosmac.html
203                and:  http://www.elf-emulation.com/1802.html
204            x)  1805 extended opcodes: Implement at least disassembly support!
205            x)  Keyboard input.
206            x)  Sound (beep only).
207            x)  Slow-down to correct speed? Wikipedia: "it was usually operated
208                at 3.58 MHz/2 to suit the requirements of the 1861 chip which
209                gave a speed of a little over 100,000 instructions per second"
210                (Note that _CHIP8_ emulation would then be even slower.)
211            x)  SCHIP48 (Super) emulation:
212                    Some more opcodes, 128x64 framebuffer, larger
213                    sprites and fonts.
214    
215    Alpha:
216            x)  OSF1 PALcode, Virtual memory support.
217            x)  PALcode replacement! PAL1E etc opcodes...?
218            x)  Interrupt/exception/trap handling.
219            x)  Floating point exception correctness.
220            x)  More work on bootup memory and register contents.
221            x)  More Alpha machine types, so it could work with
222                OpenBSD, FreeBSD, and Linux too?
223    
224    SPARC:
225            o)  Implement Adress space identifiers; load/stores etc.
226            o)  Save/restore register windows etc! Both v9 and pre-v9!
227            o)  Finish the subcc and addcc flag computation code.
228            o)  Add more registers (floating point, control regs etc)
229            o)  Exception/trap handling.
230            o)  Disassemly of some more instructions?
231            o)  Are sll etc 32-bit sign-extending or zero-extending?
232            o)  Finish the GDB register stuff.
233            x)  Floating point exception correctness.
234            o)  SPARC v8, v7 etc?
235    
236    Debugger:
237            o)  How does SMP debugging work? Does it simply use "threads"?
238                    What if the guest OS (running on an emulated SMP machine)
239                    has a usertask running, with userland threads?
240            o)  Try to make the debugger more modular and, if possible, reentrant!
241            o)  Remove the emul command? (But show network info if showing
242                    machines?)
243            o)  Evaluate expressions within []? That would allow stuff like
244                    cpu[x] where x is an expression.
245            o)  Settings:
246                    x)  Special handlers for Write!
247                            +)  MIPS coproc regs
248                            +)  Alpha/MIPS/SPARC zero registers
249                            +)  x86 64/32/16-bit registers
250                    x)  Value formatter for resulting output.
251            o)  see src/debugger.c for more
252    
253    POWER/PowerPC:
254            x)  Fix DECR timer speed, so it matches the host.
255            x)  NetBSD/prep 3.x triggers a possible bug in the emulator:
256                <wdc_exec_command(0xd005e514,0xd60cdd30,0,8,..)>
257                  <ata_get_xfer(0,0xd60cdd30,0,8,..)>
258                    <0x26c550(&ata_xfer_pool,2,0,8,..)>
259                    <0x35c71c(0x3f27000,0,52,8,..)>
260                  <ata_exec_xfer(0xd005e4c8,0x3f27000,0,13,..)>
261                    <atastart(0xd005e4c8,0x3f27000,0,13,..)>
262                      <__wdccommand_start(0xd005e4c8,0x3f27000,0,13,..)>
263                        <bsw1(&prep_isa_io_space_tag,0x800001f6,0,176,..)>
264                    [ wdc: write to SDH: 0xb0 (sectorsize 2, lba=1, drive 1, head 0) ]
265                        <wdcwait(0xd005e4c8,72,64,0xbb8,..)>
266                          <0x198120(0xd005e4c8,72,64,0xbb8,..)>
267                            <bsr1(&prep_isa_io_space_tag,0,0,0xbb8,..)>
268                            <delay(100,0,0,0xbb8,..)>
269                Note: <bsr1(&prep_isa_io_space_tag,0,0,0xbb8,..)>
270            x)  PPC optimizations; instr combs
271            x)  64-bit stuff: either Linux on G5, or perhaps some hobbyist
272                    version of AIX? (if there exists such a thing)
273            x)  macppc: adb controller; keyboard (for framebuffer mode)
274            x)  make OpenBSD/macppc work (PCI controller stuff)
275            x)  Floating point exception correctness.
276            x)  Alignment exceptions.
277    
278    PReP:
279            Clock time! ("Bad battery blah blah")
280    
281    Algor:
282            o)  Other models than the P5064?
283            o)  PCI interrupts... needed for stuff like the tlp NIC?
284    
285    BeBox:
286            o)  Interrupts. There seems to be a problem with WDC interrupts
287                "after a short while", although a few interrupts get through?
288            o)  Perhaps find a copy of BeOS and try it?
289    
290    HPCmips:
291            x)  Mouse/pad support! :)
292            x)  A NIC? (As a PCMCIA device?)
293    
294    AVR:
295            o)  Everything.
296    
297    ARM:
298            o)  See netwinder_reset() in NetBSD; the current "an internal error
299                occured" message after reboot/halt is too ugly.
300            o)  ARM "wait"-like instruction?
301            o)  try to get netbsd/evbarm 3.x or 4.x running (iq80321)
302            o)  make the xscale counter registers (ccnt) work
303            o)  make the ata controller usable for FreeBSD!
304            o)  Zaurus emulation, for e.g. OpenBSD/zaurus
305            o)  Debian/cats crashes because of unimplemented coproc stuff.
306                fix this?
307    
308    Test machines:
309            o)  dev_fb block fill and copy
310            o)  dev_fb draw characters (from the built-in font)?
311            o)  dev_fb input device? mouse pointer coordinates and buttons
312                    (allow changes in these to cause interrupts as well?)
313            o)  Redefine the halt() function so that it stops "sometimes
314                soon", i.e. usage in demo code should be:
315                    for (;;) {
316                            halt();
317                    }
318    
319    Better CD Image file support:
320            x)  Support CD formats that contain more than 1 track, e.g.
321                CDI files (?). These can then contain a mixture of e.g. sound
322                and data tracks, and booting from an ISO filesystem path
323                would boot from [by default] the first data track.
324                (This would make sense for e.g. Dreamcast CD images, or
325                possibly other live-CD formats.)
326    
327    Networking:
328            x)  Fix performance problems caused by only allowing a
329                single TCP packet to be unacked.
330            x)  Don't hardcode offsets into packets!
331            x)  Test with lower than 100 max tcp/udp connections,
332                to make sure that reuse works!
333            x)  Make OpenBSD work better as a guest OS!
334            x)  DHCP? Debian doesn't actually send DHCP packets, even
335                    though it claims to? So it is hard to test.
336            x)  Multiple networks per emulation, and let different
337                NICs in machines connect to different networks.
338            x)  Support VDE (vde.sf.net)? Easiest/cleanest (before a
339                redesign of the network framework has been done) is
340                probably to connect it using the current (udp) solution.
341            x)  Allow SLIP connections, possibly PPP, in addition to
342                ethernet?
343    
344    Cache simulation:
345            o)  Command line flags for:
346                    o)  CPU endianness?
347                    o)  Cache sizes? (multiple levels)
348            o)  Separate from the CPU concept, so that multi-core CPUs sharing
349                e.g. a L2 cache can be simulated (?)
350            o)  Instruction cache emulation is easiest (if separate from the
351                data cache); similar hack as the S;I; hack in cpu_dyntrans.c.
352                NOTE: if the architecture has a delay slot, then an instruction
353                slot can actually be executed as 2 instructions.
354            o)  Data cache emulation = harder; each arch's load/store routines
355                must include support? running one instruction at a time and
356                having a cpu-dependant lookup function for each instruction
357                is another option (easier to implement, but very very slow).
358    
359    Documentation:
360            x)  Note about sandboxing/security:
361                    Not all emulated instructions fail in the way they would
362                    do on real hardware (e.g. a userspace program writing to
363                    a system register might work in GXemul, but it would
364                    fail on real hardware).  Sandbox = contain from the
365                    host OS. But the emulated programs will run "less
366                    securely".
367            x)  Try NetBSD/arc 4.x! (It seems to work with disk images!)
368            x)  NetBSD/pmax 4 install instructions: xterm instead of vt100!
369            x)  BETTER DEVICE EXAMPLES!
370                    o)  Move away from technical.html to somewhere new.
371                    o)  DEVICE_TICK
372                    o)  Implement example devices using interrupts, dyntrans
373                        memory access, etc.?
374            x)  Document the dyntrans core?
375            x)  Rewrite the section about experimental devices, after the
376                framebuffer acceleration has been implemented, and demos
377                written. (Symbolic names instead of numbers; example
378                use cases, etc. Mention demo files that use the various
379                features?)
380            x)  "a very simple linear framebuffer device (for graphics output)"
381                under "which machines does gxemul emulate" ==> better
382                description?
383            x)  Better description on how to set up a cross compiler?
384                Example for MIPS64.
385            o)  Automagic documentation generation?
386                    x)  machines, cpus, devices.
387                    x)  REMEMBER that several machines/devices can be in
388                            the same source file!
389            o)  Try to rewrite the install instructions for those machines
390                that use 3MAX into using CATS or hpcmips? (To remove the need
391                to use a raw ffs partition, using up all of the disk image.)
392    
393    More generic out_of_memory error reporting, and check everywhere!
394            Causes: OpenBSD has low default limits for normal users.
395                    Host is 32-bit? (32-bit hosts are limited to 4 GB or less
396                    of userspace memory.)
397                    You are actually low on RAM. (As trivial as this might sound,
398                    Unix systems usually allow processes to allocate virtual
399                    memory beyond the amount of RAM in the machine.)
400    
401    The Device subsystem:
402            x)  allow devices to be moved and/or changed in size (down to a
403                minimum size, etc, or up to a max size); if there is a collision,
404                return false. It is up to the caller to handle this situation!
405            x)  NOTE: Translations must be invalidated, both for
406                registering new devices, and for moving existing ones.
407                cpu->invalidate translation caches, for all CPUs that
408                are connected to a specific memory.
409            x)  keep track of interrupts and busses? actually, allowing any device
410                to be a bus might be a nice idea.
411            x)  turn interrupt controllers into devices? :-)
412            x)  refactor various clocks/nvram/cmos into one device?
413    
414    PCI:
415            x)  last write was ffffffff ==> fix this, it should be used
416                together with a mask to get the correct bits. also, not ALL
417                bits are size bits! (lowest 4 vs lowest 2?)
418            x)  add support for address fixups
419            x)  generalize the interrupt routing stuff (lines etc)
420    
421    Clocks and timers:
422            x)  DON'T HARDCODE 100 HZ IN cpu_mips_coproc.c!
423            x)  Test the 8253? Right now it doesn't seem to be used?
424            x)  NetWinder timeofday is incorrect!
425            x)  Cobalt TOD is incorrect!
426            x)  Go through all other machines, one by one, and fix them.
427    
428    Config file parser:
429            o)  Rewrite it from scratch!
430            o)  Usage of any expression available through the debugger
431            o)  Allow interrupt controllers to be added! and interrupts
432                to be used in more ways than before
433            o)  Support for running debugger commands (like the -c
434                command line option)
435    
436    Floating point layer:
437            o)  make it common enough to be used by _all_ emulation modes
438            o)  implement correct error/exception handling and rounding modes
439            o)  implement more helper functions (i.e. add, sub, mul...)
440            o)  non-IEEE modes (i.e. x86)?
441    
442    Userland emulation:
443            x)  Lots of stuff; freebsd and netbsd (and linux?) syscalls.
444            x)  Dynamic linking? Hm.
445    
446    Sound:
447            x)  generic sound framework
448            x)  add one or more sound cards as devices; add a testmachine
449                sound card first?
450            x)  Dreamcast sound? Generic PCI sound cards?
451    
452    ASC SCSI controller:
453            x)  NetBSD/arc 2.0 uses the ASC controller in a way which GXemul
454                cannot yet handle. (NetBSD 1.6.2 works ok.) (Possibly a problem
455                in NetBSD itself, http://mail-index.netbsd.org/source-changes/
456                2005/11/06/0024.html suggests that.)
457                NetBSD 4.x seems to work? :)
458    
459    Caches / memory hierarchies: (this is mostly MIPS-specific)
460            o)  src/memory*.c: Implement correct cache emulation for
461                all CPU types. (currently only R2000/R3000 is implemented)
462                (per CPU, multiple levels should be possible, associativity etc!)
463            o)  R2000/R3000 isn't _100%_ correct, just almost correct :)
464            o)  Move the -S (fill mem with random) functionality into the
465                memory.c subsystem, not machine.c or wherever it is now
466            o)  ECC stuff, simulation of memory errors?  (Machine dependent)
467            o)  More than 4GB of emulated RAM, when run on a 32-bit host?
468                (using manual swap-out of blocks to disk, ugly)
469            o)  A global command line option should be used to turn
470                cache emulation on or off. When off, caches should be
471                faked like they are right now. When on, caches and
472                memory latencies should be emulated as correctly as
473                possible.
474    
475    File/disk/symbol handling:
476            o)  Make sure that disks can be added/removed during runtime!
477                (Perhaps this needs a reasonably large re-write.)
478            o)  Remove some of the complexity in file format guessing, for
479                    Ultrix kernels that are actually disk images?
480            o)  Better handling of tape files      
481            o)  Read function argument count and types from binaries? (ELF?)
482            o)  Better demangling of C++ names. Note: GNU's C++ differs from e.g.
483                Microsoft's C++, so multiple schemes must be possible. See
484                URL at top of src/symbol_demangle.c for more info.
485    
486    Userland ABI emulation:
487            o)  see src/useremul.c
488    
489    Better framebuffer and X-windows functionality:
490            o)  Generalize the update_x1y1x2y2 stuff to an extend-region()
491                function...
492            o)  -Yx sometimes causes crashes.
493            o)  Simple device access to framebuffer_blockcopyfill() etc,
494                and text output (using the built-in fonts), for dev_fb.
495            o)  CLEAN UP the ugly event code
496            o)  Mouse clicks can be "missed" in the current system; this is
497                not good. They should be put on a stack of some kind.
498            o)  More 2D and 3D framebuffer acceleration.
499            o)  Non-resizable windows?  Or choose scaledown depending
500                    on size (and center the image, with a black border).
501            o)  Different scaledown on different windows?
502            o)  Non-integral scale-up? (E.g. 640x480 -> 1024x768)
503            o)  Switch scaledown during runtime? (Ala CTRL-ALT-plus/minus)
504            o)  Bug reported by Elijah Rutschman on MacOS with weird
505                keys (F5 = cursor down?).
506            o)  Keyboard and mouse events:
507                    x)  Do this for more machines than just DECstation
508                    x)  more X11 cursor keycodes
509                    x)  Keys like CTRL, ALT, SHIFT do not get through
510                        by themselves (these are necessary for example
511                        to change the font of an xterm in X in the
512                        emulator)
513            o)  Generalize the framebuffer stuff by moving _ALL_ X11
514                    specific code to src/x11.c!
515    

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