/[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 6 by dpavlin, Mon Oct 8 16:18:11 2007 UTC revision 30 by dpavlin, Mon Oct 8 16:20:40 2007 UTC
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1  $Id: TODO,v 1.133 2005/05/25 06:40:16 debug Exp $  $Id: TODO,v 1.343 2006/08/14 18:46:30 debug Exp $
2    
3  Here's a short list of what I have left to do on GXemul. This file is a mess.  Hm. This file is in random order, and not all parts of it are up-to-date.
 Order is random. Don't trust it to be up-to-date.  
4    
5          Caches / memory hierarchies: (this is mostly MIPS-specific)  
6                  o)  MIPS coproc.c: bits in config registers should reflect  Implementation:
7                      correct cache sizes for _all_ CPU types. (currently only          x)  ARM "wait"-like instruction.
8                      implemented for R4000, R1x000, and a few others)          x)  CLOCK FRAMEWORK!
9                  o)  src/memory*.c: Implement correct cache emulation for          x)  Mouse support for NetBSD/pmax 4.x!
10                      all CPU types. (currently only R2000/R3000 is implemented)          x)  See netwinder_reset() in NetBSD; the current "an internal error
11                      (per CPU, multiple levels should be possible,              occured" message after reboot/halt is too ugly.
12                      associativity etc!)          x)  64-bit ranges in src/cpus/memory_mips_v2p.c
13                  o)  R2000/R3000 isn't _100%_ correct, just almost correct :)          x)  Revert the dyntrans page template experiment? Hm.
14                  o)  Move the -S (fill mem with random) functionality into the          x)  Refactor the cpu type detection/initialization/listing.
15                      memory.c subsystem, not machine.c or wherever it is now                  Macro, which can be used as long as the cpu definitions
16                  o)  ECC stuff, simulation of memory errors?  (Machine dependant)                  contain a 'name'?
17                  o)  More than 4GB of emulated RAM, when run on a 32-bit host?          x)  Testmachine includes:
18                      (using manual swap-out of blocks to disk, ugly)                  + dev_fb block fill and copy
19                  o)  A global command line option should be used to turn                  + dev_fb draw characters (from the built-in font)?
20                      cache emulation on or off. When off, caches should be                  + dev_fb input device? mouse pointer coordinates and buttons
21                      faked like they are right now. When on, caches and                          (allow changes in these to cause interrupts as well?)
22                      memory latencies should be emulated as correctly as                  + Redefine the halt() function so that it stops "sometimes
23                      possible.                    soon", i.e. usage in demo code should be:
24                            for (;;) {
25          Network layer:                                  halt();
26                  o)  Multiple networks per emulation, and let different                          }
27                      NICs in machines connect to different networks.          x)  Continue on SPARC emulation
28                  o)  Network across multiple hosts.                  + Enable it in the configure script as soon as it can
29                  o)  Fixed MAC addresses for NICs, fixed IPv4 addresses if                    run all the demo programs.
30                      DHCP or RARP is used.          x)  Continue on Alpha emulation  (virtual memory, etc). Cleanup.
31                  o)  many other issues: see src/net.c          x)  Nicer MIPS status bits in register dumps.
32            x)  Alignment exceptions (MIPS, PPC, ARM?, ...)
33          Configure script:          x)  Rewrite the networking stack; make OpenBSD work better as a guest
34                  o)  Only enable Alpha prefetch on pca56 etc, not on ev4, ev5.              OS, fix the performance problems, make Linux work with DHCP, etc.
35                  o)  Use getopts?              Support VDE (vde.sf.net)? Allow SLIP connections, possibly PPP,
36                  o)  X11 libs and headers via command line option?              in addition to ethernet?
37                  o)  Verify that the configure script, building and running          x)  Implement more ethernet NICs.
38                      the emulator works on some platforms:          x)  IOP (I2O) device?
39                          +)  Irix, AIX, QNX  
40                          +)  MacOS X  (I've not tried this personally yet)  Documentation:
41                          +)  Ultrix using gcc? (Inside the emulator)          x)  "Install netbsd/pmax first" => only use the install kernel?
42            x)  Rewrite the section about experimental devices, after the
43          CPU emulation:              framebuffer acceleration has been implemented, and demos
44                  o)  Binary translation:              written. (Symbolic names instead of numbers; example
45                          +)  use an Intermediate Representation!              use cases, etc. Mention demo files that use the various
46                          +)  recursive translation?              features?)
47                          +)  basic blocks instead of one-instruction? :)          x)  "a very simple linear framebuffer device (for graphics output)"
48                          +)  on Alpha: don't assume pca56-like byte load/store?              under "which machines does gxemul emulate" ==> better
49                          +)  write backends for UltraSparc and MIPS              description?
50                          +)  see src/bintrans.c for more info          x)  Better description on how to set up a cross compiler?
51                  o)  All the non-MIPS modes need a bit of work.              Example for MIPS64.
52    
53          MIPS CPU emulation:  Long-term design:
54                  o)  Instructions:          x)  Instruction combination collisions? How to avoid easily...
55                          o)  Regression tests (see tests/README for more info):          x)  Think about how to do both SHmedia and SHcompact in a reasonable
56                                  o)  Floating point exception handling, and              way!
57                                          add more instructions.          o)  Actually use the settings object, better debugger stuff, etc!
58                                  o)  Finish the MIPS16 translator, and test it!          o)  Debugger command for enabling/disabling instruction statistics
59                                  o)  MIPS ISA I, II, III, IV              during runtime.   machine.statistics = on|off
60                                  o)  MIPS V (SIMD vector stuff?)          x)  MAINBUS REDESIGN!
61                                  o)  MDMX  (MIPS Digital Media Extension)          x)  PCI redesign... I need to read up on how PCI actually works :)
62                                  o)  MIPS 3D          x)  Clock framework! Go through all clock devices, make sure they
63                                  o)  MIPS MT (Multi-thread stuff) (What's this?)              return correct data, and run at correct speeds!
64                          o)  Warn about mis-used bit fields (ie bits that          x)  Dyntrans with valgrind-inspired memory checker. (In memory_rw,
65                              should be all zeroes, warn about if they are not)!              it would be reasonably simple to add; in each individual fast
66                              Both for coprocessor registers and for instruction              load/store routine = a lot more work, and it would become
67                              opcodes.              kludgy very fast.)
68                          o)  the special2 stuff is a mess right now          x)  Dyntrans with SMP... lots of work to be done here.
69                          o)  warn and/or cause exceptions for unimplemented          x)  Dyntrans with cache emulation... lots of work here as well.
70                              instructions (depending on CPU type)          x)  Reimplement the config file parser from scratch.
71                  o)  R2000/R3000:  
72                          x)  R3000 "tri-byte stores". (What's this?)  -------------------------------------------------------------------------------
73                  o)  R4000 and others:  
74                          x)  watchhi/watchlo exceptions, and other exception  Simple Valgrind-like checks?
75                              handling details          o)  Mark every address with bits which tell whether or not the address
76                  o)  R10000 and others:  (R12000, R14000 ?)              has been written to.
77                          x)  memory space, exceptions, ...          o)  What should happen when programs are loaded?  Text/data, bss (zero
78                          x)  use cop0 framemask for tlb lookups              filled). But stack space and heap is uninitialized.
79                              (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)  Uninitialized local variables:
80                  o)  Implement load delays?  Warnings on interlocks.                  A load from a place on the stack which has not previously
81                  o)  Implement all coprocessor 0 bits / functions.                  been stored to => warning. Increasing the stack pointer using
82                          x)  coproc 0 selectors! (R4000 ?)                  any available means should reset the memory to uninitialized.
83                  o)  R4300 (nintendo64, no mmu?), R5900 (playstation2, weird          o)  If calls to malloc() and free() can be intercepted:
84                          TLB/cache? 128-bit GPRs, new instructions),                  o)  Access to a memory area after free() => warning.
85                          4K (note: NOT R4000), 5K (note: NOT R5000),                  o)  Memory returned by malloc() is marked as not-initialized.
86                          R6000 (ISA II), R8000                  o)  Non-passive, but good to have: Change the argument
87                  o)  Multi-cpu stuff:                      given to malloc, to return a slightly larger memory
88                          +)  SGI's NUMA architecture. Study                      area, i.e.  margin_before + size + margin_after,
89                                  x)  Linux sources                      and return the pointer  + margin_before.
90                                  x)  SGI's specs on NUMA address space                      Any access to the margin_before or _after space results
91                          +)  Ultrix?  NetBSD doesn't do SMP on MIPS yet :-(                      in warnings. (free() must be modified to free the
92                          +)  Own experiments with ycx2.                      actually allocated address.)
93    
94          Emulation of specific machines and devices:  SMP:
95                  o)  Clean up stuff to make it possible to emulate multiple          o)  dev_mp doesn't work well with dyntrans yet
96                      (different) machines simultaneously.          o)  In general, IPIs, CAS, LL/SC etc must be made to work with dyntrans
97                  o)  Use same clock for all emulations and machines.  
98                  o)  Clean up the device stuff (registering of devices etc)  MIPS:
99                  o)  Various SCSI and IDE controllers          +)  Some more work on opcodes.
100                  o)  PS/2-style keyboard controller (for several machines)                  x) The "wait" instruction. How to implement this functionality?
101                  o)  Generic busses;                          (SMP, non-MIPS, interrupt correctness, host idling, ...)
102                          x)  PCI:  i/o and interrupts                  x) MIPS64 revision 2.
103                          x)  QBus-22 (DECsystem 5500, 5400?)                          o)  Find out which actual CPUs implement the rev2 ISA!
104                  o)  DECstations (pmax):                  x) _MAYBE_ TX79 and R5900 actually differ in their
105                          x)  ioasic                     opcodes? Check this carefully!
106                          x)  framebuffers:          o)  Dyntrans: Count register updates are probably not 100% correct yet.
107                                  +)  better cursor support, overlays?,          o)  Refactor code for performance and readability/maintainability.
108                                  +)  2D/3D acceleration, PX[G]          o)  DROTR32 and similar MIPS64 rev 2 instructions, which have
109                          x)  status words / control words, make this more              a rotation bit which differs from previous ISAs.
110                                  portable/cleaner          o)  EI and DI instructions for MIPS64/32 rev 2. NOTE: These are
111                          x)  scsi controller(s): sii, DMA for asc              _NOT_ the same as for R5900!
112                          x)  serial controllers: ssc, scc (and more work on dc?)          o)  (Re)implement 128-bit loads/stores for R5900.
113                          x)  nvram on decstation 5000/125:  when using X11,          o)  R4000 and others:
114                                  set console=g or similar                  x)  watchhi/watchlo exceptions, and other exception
115                          x)  DECstation 5840? "xbi-based SMP"                      handling details
116                  o)  SGI and ARC machines (sgimips, arc):          o)  R10000 and others:  (R12000, R14000 ?)
117                          x)  IP32 ("O2"): (Lots of stuff)                  x)  memory space, exceptions, ...
118                                  +)  mec (ethernet)                  x)  use cop0 framemask for tlb lookups
119                                  +)  pci                      (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)
120                                  +)  ahc (scsi)  
121                                  +)  ps2 kbd  Dyntrans:
122                                  +)  memory controller          x)  Redesign/rethink the delay slot mechanism used for e.g. MIPS,
123                                  +)  framebuffer/graphics                  so that it caches a translation (that is, an instruction
124                                  +)  caches                  word and the instr_call it was translated to the last
125                          x)  more ARCBIOS stuff                  time), so that it doesn't need to do slow
126                          x)  Memory/interrupt controllers                  to_be_translated for each end of page?
127                          x)  IP30 (Linux with graphics support?)          x)  Program Counter statistics:
128                          x)  SMP / NUMA?  (SGI and various ARC machines)                  Per machine? What about SMP? All data to the same file?
129                  o)  Playstation 2:                  A debugger command should be possible to use to enable/
130                          Hardware:  OHCI usb controller, keyboard, ...                  disable statistics gathering.
131                  o)  Cobalt:  PCI and interrupt system, ethernet,                  Configuration file option!
132                          harddisk controller(s)          x)  Common fatal_abort() function, which drops into the debugger
133                  o)  Less interesting platforms:                  without continuing.
134                          o)  newsmips:          x)  INVALIDATION should cause translations in _all_ cpus to be
135                                  o)  NetBSD/newsmips, get it to detect a "real"              invalidated, e.g. on a write to a write-protected page
136                                      model, right now everything is 100% bogus              (containing code)
137                          o)  mipsco? (NetBSD)          x)  16-bit encodings? (MIPS16, ARM Thumb, SH3, ...)
138                          o)  wgrisc? (big endian R3000, in OpenBSD's attic)          x)  Lots of other stuff: see src/cpus/README_DYNTRANS
139                          o)  other embedded / evaluation MIPS boards          x)  true recompilation backend? think carefully about this,
140                          o)  Playstation 1? R3000A. Weird hardware?              experiment in a separate project (not in GXemul)
141                                  No FPU, but something as coproc 2.                  o) First test would be to just implement a simple
142                          o)  Nintendo 64, http://www.nintendo.com/systems/n64/n64_specs.jsp                     instruction such as MIPS' addiu or lui, on AMD64
143                                  (R4300, 4MB RAM, really weird memory map)                     hosts...
144                  o)  non-MIPS          x)  Idle loop detection? (Depends on target.) Could be turned
145                into usleep(1) or similar on the host... except when doing
146          File/disk handling:              e.g. SMP emulation. Then it becomes trickier.
147                  o)  More than one type of disk in a machine (say, IDE + FLOPPY,  
148                      or SCSI + IDE); how to handle this nicely?  Transputer:
149                  o)  Read function argument count and types from binaries? (ELF?)          x)  Implement support for Helios binaries.
150                  o)  ELF: separate LE/BE (MIPS instruction format) from LSB/MSB          x)  Stack and register contents at startup?
151                          (ELF structure format)?          x)  Figure out how to boot an entire Helios distribution.
152                  o)  Better handling of tape files          x)  Implement all instructions. :)
153                  o)  gzip support (also for non-ISO9660 files)  
154    Alpha:
155          Userland ABI emulation:          o)  Virtual memory (tlbs etc)
156                  o)  see src/useremul.c          o)  Get {NetBSD,OpenBSD,Linux}/alpha booting. :)
157    
158          Terminal based interactive debugger:  SPARC:
159                  o)  see src/debugger.c          o)  Load/stores to alternate address spaces!
160            o)  Save/restore register windows etc!
161          Terminal/console stuff:          o)  Finish the subcc and addcc flag computation code.
162                  o)  allow emulated serial ports to be connected to the outside          o)  Add more registers (floating point, control regs etc)
163                      world in a more generic way, or even to other emulated          o)  Disassemly of some more instructions?
164                      machines(!)          o)  Are sll etc 32-bit sign-extending or zero-extending?
165            o)  Finish the GDB register stuff.
166          GDB interface? (Maybe not necessary; the built-in debugger feels          o)  SPARC v8, v7 etc?
167          more useful.)  
168    Debugger:
169          GUI, interactive debugger?  GTK+?  (The GUI _must be optional_!)          o)  How does SMP debugging work? Does it simply use "threads"?
170                  o)  Breakpoints (complex expressions? combinations of register                  What if the guest OS (running on an emulated SMP machine)
171                          states, memory accesses and so on)                  has a usertask running, with userland threads?
172                  o)  Instruction trace          o)  Try to make the debugger more modular and, if possible, reentrant!
173                  o)  Disassembly of RAM (_NOT_ the same as instruction trace)          o)  Remove the emul command? (But show network info if showing
174                  o)  Function call trace                  machines?)
175                  o)  Inspection of CPU registers/state, coprocessor          o)  Generalize the expression evaluator. (debugger_expr.c?)
176                          registers/state, any device registers/state/contents                  settable variables      ("show nr of instructions on average")
177                          o)  Framebuffers in windows / tabs.                  emul[x]                 defaults to current emul
178                          o)  Contents of RAM                  machine[x]              defaults to current machine
179                  o)  "Start new emulation" should allow amount of                  cpu[x]                  defaults to currently focused cpu
180                          RAM and nr of cpus to easily be specified.                  registers               cpu arch dependent (#-prefix)
181                          Multiple simultaneous machines should be possible.                  symbols                 @-prefix
182                  o)  Disk images.                  numeric constants       decimal, hex, and octal ($-prefix)
183                    boolean                 yes,no, true,false
184          Regression tests:                  operators (+ - * / % & | ^ !)
185                  o)  see tests/                  parentheses for grouping subexpressions
186                    NOTE: the change from % to # for register prefix!
187          Save state of the whole emulated machine, to be able to load it back                  examples:
188                  in later?  (Memory, all device's states, all registers and                                  emul[0].machine[2].cpu[0].pc
189                  so on.  Like taking a snapshot. (SimOS seems to do this,                                  machine[test2].cpu[1].ra = main
190                  according to its website.))                                  settings.show_trace_tree = yes
191    
192          Better X-windows functionality:                  Settings:
193                  o)  CLEAN UP the ugly event code                          o)  Remove a setting.
194                  o)  Mouse clicks can be "missed" in the current system; this is                          o)  Read/write a setting given a name. (Read as
195                      not good. They should be put on a stack of some kind.                              string and/or int64_t simultaneously?)
196                  o)  More 2D and 3D framebuffer acceleration.                          o)  Warnings when exiting the emulator, if the
197                  o)  Non-resizable windows?  Or choose scaledown depending                              settings have not been removed exactly in
198                          on size (and center the image, with a black border).                              the same way as they were added? This would
199                  o)  Different scaledown on different windows?                              improve code cleanliness in the long term.
200                  o)  Switch scaledown during runtime? (Ala CTRL-ALT-plus/minus)                              (I.e. require a corresponding _destroy()
201                  o)  Keyboard and mouse events:                              function for all _new functions... machine_
202                          x)  Do this for more machines than just DECstation                              cpu_ etc.)
203                          x)  more X11 cursor keycodes  
204                          x)  Keys like CTRL, ALT, SHIFT do not get through                  Help command should have subsections! One for "expressions",
205                              by themselves (these are necessary for example                  mirrored in the documentation, but the internal help should
206                              to change the font of an xterm in X in the                  be the one that should be considered correct.
207                              emulator)          o)  see src/debugger.c for more
208                  o)  Generalize the framebuffer stuff by moving _ALL_ X11  
209                          specific code to src/x11.c!  POWER/PowerPC:
210            x)  PPC optimizations; instr combs
211          Statistics:  (this could be interesting)          x)  64-bit stuff: either Linux on G5, or perhaps some hobbyist
212                  o)  Save to file and show graphics. It should be possible to                  version of AIX? (if there exists such a thing)
213                      run gxemul after a simulation to just show the graphics,          x)  find and fix the bug which causes NetBSD/macppc to fail after
214                      or convert to a .ppm or .tga or similar.              an install!
215                  o)  memory accesses (to measure cache efficiency and          x)  macppc: adb controller; keyboard (for framebuffer mode)
216                          page coloring efficiency)          x)  make OpenBSD/macppc work (PCI controller stuff)
217                  o)  nr of simultaneous ASIDs in use in the TLB, for MIPS  
218                  o)  percentage of time spent in different "states", such as  Algor:
219                      running userland code, kernel code, or idling (for CPUs          PCI interrupts... needed or stuff like the tlp NIC?
220                      that have such an instruction, or whenever the PC is  
221                      inside a specific idle-function (address range)).  ARM:
222                      Possible additional state (for example on R3000): caches          o)  try to get netbsd/evbarm 3.x running (iq80321)
223                      disabled.          o)  make the xscale counter registers (ccnt) work
224                  o)  position of read/write on (SCSI) disks          o)  make the ata controller usable for FreeBSD!
225            o)  zaurus for openbsd...
226            o)  debian/cats crashes because of unimplemented coproc stuff.
227                fix this?
228    
229    Cache simulation:
230            o)  Command line flags for:
231                    o)  CPU endianness?
232                    o)  Cache sizes? (multiple levels)
233            o)  Separate from the CPU concept, so that multi-core CPUs sharing
234                e.g. a L2 cache can be simulated (?)
235            o)  Instruction cache emulation is easiest (if separate from the
236                data cache); similar hack as the S;I; hack in cpu_dyntrans.c.
237                NOTE: if the architecture has a delay slot, then an instruction
238                slot can actually be executed as 2 instructions.
239            o)  Data cache emulation = harder; each arch's load/store routines
240                must include support? running one instruction at a time and
241                having a cpu-dependant lookup function for each instruction
242                is another option (easier to implement, but very very slow).
243    
244    Documentation:
245            o)  machines, cpus, devices.
246            o)  Automagic documentation generation:
247                    x)  REMEMBER that several machines/devices can be in
248                            the same source file!
249            o)  Try to rewrite the install instructions for those machines
250                that use 3MAX into using CATS? (To remove the need to a raw
251                ffs partition using up all of the disk image.)
252    
253    More generic out_of_memory error reporting, and check everywhere!
254            Causes: OpenBSD has low default limits for normal users.
255                    Host is 32-bit? (32-bit hosts are limited to 4 GB or less
256                    of userspace memory.)
257                    You are actually low on RAM. (As trivial as this might sound,
258                    Unix systems usually allow processes to allocate virtual
259                    memory beyond the amount of RAM in the machine.)
260    
261    Breakpoints: 32-bit vs 64-bit sign extension for MIPS, warnings, etc.
262            Use the debugger's symbolic name stuff. (which will have to be
263            extended soon to support stuff like  "2*x + symbol + y" etc. cool
264            stuff)
265    
266    The Device subsystem:
267            x)  allow devices to be moved and/or changed in size (down to a
268                minimum size, etc, or up to a max size)
269            x)  keep track of interrupts and busses? actually, allowing any device
270                to be a bus might be a nice idea.
271            x)  turn interrupt controllers into devices? :-)
272            x)  refactor various clocks/nvram/cmos into one device?
273    
274    Clocks:
275            x)  General framework for automagic clock adjustment for _all_
276                kinds of clocks and timers. (Which should be possible to turn
277                off, of course, like the way DECstation emulation works now.)
278    
279    PCI:
280            x)  last write was ffffffff ==> fix this, it should be used
281                together with a mask to get the correct bits. also, not ALL
282                bits are size bits! (lowest 4 vs lowest 2?)
283            x)  add support for address fixups
284            x)  generalize the interrupt routing stuff (lines etc). this should
285                be per machine? or per bus, that's better
286            x)  add a "pcn" NIC (AMD PCnet32 Lance 79c970 (PCI 1022:2000)),
287                could be useful for several machine modes (Malta, Algor, evbarm,
288                hp700?, macppc, etc.)
289    
290    Network layer:
291            o)  DHCP (for Debian and BSD installers :-)
292            o)  increase performance
293            o)  don't rely on NetBSD-ish usage
294            o)  Multiple networks per emulation, and let different
295                NICs in machines connect to different networks.
296            o)  many other issues: see src/net.c
297    
298    Busses:
299            o)  Redesign the entire "mainbus" concept!
300            o)  Busses should be placed in a hierarchical tree!
301            o)  Easily configurable interrupt routing in SMP systems.
302            o)  Specific clock/bus speeds, cpu speeds etc.
303            o)  Synchronization over network? or at least in dyntrans within
304                one emulated machine
305            o)  dev->bus: TurboChannel, PCMCIA, ADB?
306    
307    Config file parser:
308            o)  Rewrite it from scratch!
309            o)  Usage of any expression available through the debugger
310            o)  Support for running debugger commands (like the -c
311                command line option)
312    
313    Floating point layer:
314            o)  make it common enough to be used by _all_ emulation modes
315            o)  implement more stuff
316            o)  non-IEEE modes (i.e. x86)?
317    
318    Userland emulation:
319            x)  Lots of stuff; freebsd and netbsd (and linux?) syscalls.
320            x)  Dynamic linking? Hm.
321    
322    Sound:
323            x)  generic sound framework
324            x)  add one or more sound cards as devices
325    
326    ASC SCSI controller:
327            x)  NetBSD/arc 2.0 uses the ASC controller in a way which GXemul
328                cannot yet handle. (NetBSD 1.6.2 works ok.) (Possibly a problem
329                in NetBSD itself, http://mail-index.netbsd.org/source-changes/
330                2005/11/06/0024.html suggests that.)
331    
332    Caches / memory hierarchies: (this is mostly MIPS-specific)
333            o)  src/memory*.c: Implement correct cache emulation for
334                all CPU types. (currently only R2000/R3000 is implemented)
335                (per CPU, multiple levels should be possible, associativity etc!)
336            o)  R2000/R3000 isn't _100%_ correct, just almost correct :)
337            o)  Move the -S (fill mem with random) functionality into the
338                memory.c subsystem, not machine.c or wherever it is now
339            o)  ECC stuff, simulation of memory errors?  (Machine dependent)
340            o)  More than 4GB of emulated RAM, when run on a 32-bit host?
341                (using manual swap-out of blocks to disk, ugly)
342            o)  A global command line option should be used to turn
343                cache emulation on or off. When off, caches should be
344                faked like they are right now. When on, caches and
345                memory latencies should be emulated as correctly as
346                possible.
347    
348    File/disk/symbol handling:
349            o)  Remove some of the complexity in file format guessing, for
350                    Ultrix kernels that are actually disk images?
351            o)  Better handling of tape files
352            o)  Read function argument count and types from binaries? (ELF?)
353            o)  Better demangling of C++ names. Note: GNU's C++ differs from e.g.
354                Microsoft's C++, so multiple schemes must be possible. See
355                URL at top of src/symbol_demangle.c for more info.
356    
357    Userland ABI emulation:
358            o)  see src/useremul.c
359    
360    Terminal/console:
361            o)  allow emulated serial ports to be connected to the outside
362                world in a more generic way, or even to other emulated
363                machines(?)
364    
365    Save state of the whole emulated machine, to be able to load it back
366            in later?  (Memory, all device's states, all registers and
367            so on.  Like taking a snapshot. (SimOS seems to do this,
368            according to its website.))
369    
370    Better framebuffer and X-windows functionality:
371            o)  -Yx sometimes causes crashes.
372            o)  Simple device access to framebuffer_blockcopyfill() etc,
373                and text output (using the built-in fonts), for dev_fb.
374            o)  CLEAN UP the ugly event code
375            o)  Mouse clicks can be "missed" in the current system; this is
376                not good. They should be put on a stack of some kind.
377            o)  More 2D and 3D framebuffer acceleration.
378            o)  Non-resizable windows?  Or choose scaledown depending
379                    on size (and center the image, with a black border).
380            o)  Different scaledown on different windows?
381            o)  Switch scaledown during runtime? (Ala CTRL-ALT-plus/minus)
382            o)  Bug reported by Elijah Rutschman on MacOS with weird
383                keys (F5 = cursor down?).
384            o)  Keyboard and mouse events:
385                    x)  Do this for more machines than just DECstation
386                    x)  more X11 cursor keycodes
387                    x)  Keys like CTRL, ALT, SHIFT do not get through
388                        by themselves (these are necessary for example
389                        to change the font of an xterm in X in the
390                        emulator)
391            o)  Generalize the framebuffer stuff by moving _ALL_ X11
392                    specific code to src/x11.c!
393    
394    Statistics:  (this could be interesting)
395            o)  Save to file and show graphics. It should be possible to
396                run gxemul after a simulation to just show the graphics,
397                or convert to a .ppm or .tga or similar.
398            o)  memory accesses (to measure cache efficiency and
399                    page coloring efficiency)
400            o)  nr of simultaneous ASIDs in use in the TLB, for MIPS
401            o)  percentage of time spent in different "states", such as
402                running userland code, kernel code, or idling (for CPUs
403                that have such an instruction, or whenever the PC is
404                inside a specific idle-function (address range)).
405                Possible additional state (for example on R3000): caches
406                disabled.
407            o)  position of read/write on (SCSI) disks
408    

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