/[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 4 by dpavlin, Mon Oct 8 16:18:00 2007 UTC revision 38 by dpavlin, Mon Oct 8 16:21:53 2007 UTC
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1  $Id: TODO,v 1.127 2005/04/15 21:39:54 debug Exp $  $Id: TODO,v 1.476 2007/04/14 05:39:47 debug Exp $
2    
3  Here's a short list of what I have left to do on GXemul. This file is a mess.  Some things, in totally random order, that I'd like to fix:
4  Order is random. Don't trust it to be up-to-date.  (Some items in this list are probably out-to-date by now.)
5    
6    Dyntrans:
7          Caches / memory hierarchies: (this is mostly MIPS-specific)          x)  Instruction combination collisions? How to avoid easily...
8                  o)  MIPS coproc.c: bits in config registers should reflect          x)  Think about how to do both SHmedia and SHcompact in a reasonable
9                      correct cache sizes for _all_ CPU types. (currently only              way! (Or AMD64 long/protected/real, for that matter.)
10                      implemented for R4000, R1x000, and a few others)          x)  68K emulation; think about how to do variable instruction
11                  o)  src/memory*.c: Implement correct cache emulation for              lengths across page boundaries.
12                      all CPU types. (currently only R2000/R3000 is implemented)          x)  Dyntrans with valgrind-inspired memory checker. (In memory_rw,
13                      (per CPU, multiple levels should be possible,              it would be reasonably simple to add; in each individual fast
14                      associativity etc!)              load/store routine = a lot more work, and it would become
15                  o)  R2000/R3000 isn't _100%_ correct, just almost correct :)              kludgy very fast.)
16                  o)  Move the -S (fill mem with random) functionality into the          x)  Dyntrans with SMP... lots of work to be done here.
17                      memory.c subsystem, not machine.c or wherever it is now          x)  Dyntrans with cache emulation... lots of work here as well.
18                  o)  ECC stuff, simulation of memory errors?  (Machine dependant)          x)  Remove the concept of base RAM completely; it would be more
19                  o)  More than 4GB of emulated RAM, when run on a 32-bit host?              generic to allow RAM devices to be used "anywhere".
20                      (using manual swap-out of blocks to disk, ugly)          o)  dev_mp doesn't work well with dyntrans yet
21                  o)  A global command line option should be used to turn          o)  In general, IPIs, CAS, LL/SC etc must be made to work with dyntrans
22                      cache emulation on or off. When off, caches should be          x)  Redesign/rethink the delay slot mechanism used for e.g. MIPS,
23                      faked like they are right now. When on, caches and                  so that it caches a translation (that is, an instruction
24                      memory latencies should be emulated as correctly as                  word and the instr_call it was translated to the last
25                      possible.                  time), so that it doesn't need to do slow
26                    to_be_translated for each end of page?
27          Network layer:          x)  Program Counter statistics:
28                  o)  Multiple networks per emulation, and let different                  Per machine? What about SMP? All data to the same file?
29                      NICs in machines connect to different networks.                  A debugger command should be possible to use to enable/
30                  o)  Network across multiple hosts.                  disable statistics gathering.
31                  o)  Fixed MAC addresses for NICs, fixed IPv4 addresses if                  Configuration file option!
32                      DHCP or RARP is used.          x)  Breakpoints:
33                  o)  many other issues: see src/net.c                  o) Physical vs virtual addresses!
34                    o) 32-bit vs 64-bit sign extension for MIPS, and others?
35          Configure script:          x)  INVALIDATION should cause translations in _all_ cpus to be
36                  o)  Only enable Alpha prefetch on pca56 etc, not on ev4, ev5.              invalidated, e.g. on a write to a write-protected page
37                  o)  Use getopts?              (containing code)
38                  o)  X11 libs and headers via command line option?          x)  16-bit encodings? (MIPS16, ARM Thumb, 32-bit SH on SH64)
39                  o)  Verify that the configure script, building and running          x)  Lots of other stuff: see src/cpus/README_DYNTRANS
40                      the emulator works on some platforms:          x)  Native code generation backends:
41                          +)  Irix, AIX, QNX                  o)  think carefully about this.
42                          +)  MacOS X  (I've not tried this personally yet)                  o)  simple syntax for emitting opcodes; backend implementation
43                          +)  Ultrix using gcc? (Inside the emulator)                      must be optional, so I don't have to write more code
44                        than necessary. after all, the non-native (C) code should
45          CPU emulation:                      always work.
46                  o)  Binary translation:                  o)  convert into native code only after an entire
47                          +)  use an Intermediate Representation!                          block has been translated? probably best.
48                          +)  recursive translation?                  o)  the "almost native" opcodes may be rearranged,
49                          +)  basic blocks instead of one-instruction? :)                      "peep-hole optimized", etc. and then as a separate step
50                          +)  on Alpha: don't assume pca56-like byte load/store?                      this list of almost native opcodes is written out
51                          +)  write backends for UltraSparc and MIPS                      as native code.
52                          +)  see src/bintrans.c for more info                  o)  think about delay slots at the end of a block!
53                  o)  All the non-MIPS modes need a bit of work.                  o)  x86/amd64 code generator can be very similar... perhaps
54                    o)  NOTE that generation is per _ABI_, not per host arch!
55          MIPS CPU emulation:                      the configure script must detect ABI!!!
56                  o)  Instructions:                  o)  branches to already translated code blocks can
57                          o)  Regression tests (see tests/README for more info):                          link the blocks together
58                                  o)  Floating point exception handling, and                  o)  load/store are the most important to optimize
59                                          add more instructions.  
60                                  o)  Finish the MIPS16 translator, and test it!  Simple Valgrind-like checks?
61                                  o)  MIPS ISA I, II, III, IV          o)  Mark every address with bits which tell whether or not the address
62                                  o)  MIPS V (SIMD vector stuff?)              has been written to.
63                                  o)  MDMX  (MIPS Digital Media Extension)          o)  What should happen when programs are loaded?  Text/data, bss (zero
64                                  o)  MIPS 3D              filled). But stack space and heap is uninitialized.
65                                  o)  MIPS MT (Multi-thread stuff) (What's this?)          o)  Uninitialized local variables:
66                          o)  Warn about mis-used bit fields (ie bits that                  A load from a place on the stack which has not previously
67                              should be all zeroes, warn about if they are not)!                  been stored to => warning. Increasing the stack pointer using
68                              Both for coprocessor registers and for instruction                  any available means should reset the memory to uninitialized.
69                              opcodes.          o)  If calls to malloc() and free() can be intercepted:
70                          o)  the special2 stuff is a mess right now                  o)  Access to a memory area after free() => warning.
71                          o)  warn and/or cause exceptions for unimplemented                  o)  Memory returned by malloc() is marked as not-initialized.
72                              instructions (depending on CPU type)                  o)  Non-passive, but good to have: Change the argument
73                  o)  R2000/R3000:                      given to malloc, to return a slightly larger memory
74                          x)  R3000 "tri-byte stores". (What's this?)                      area, i.e.  margin_before + size + margin_after,
75                  o)  R4000 and others:                      and return the pointer  + margin_before.
76                          x)  watchhi/watchlo exceptions, and other exception                      Any access to the margin_before or _after space results
77                              handling details                      in warnings. (free() must be modified to free the
78                  o)  R10000 and others:  (R12000, R14000 ?)                      actually allocated address.)
79                          x)  memory space, exceptions, ...  
80                          x)  use cop0 framemask for tlb lookups  MIPS:
81                              (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)  Nicer MIPS status bits in register dumps.
82                  o)  Implement load delays?  Warnings on interlocks.          o)  Alignment exceptions.
83                  o)  Implement all coprocessor 0 bits / functions.          o)  Floating point exception correctness.
84                          x)  coproc 0 selectors! (R4000 ?)          o)  Fix this? Triggered by NetBSD/sgimips? Hm:
85                  o)  R4300 (nintendo64, no mmu?), R5900 (playstation2, weird                  to_be_translated(): TODO: unimplemented instruction:
86                          TLB/cache? 128-bit GPRs, new instructions),                  000000000065102c: 00200800 (d)  rot_00  at,zr,0
87                          4K (note: NOT R4000), 5K (note: NOT R5000),          o)  Some more work on opcodes.
88                          R6000 (ISA II), R8000                  x) MIPS64 revision 2.
89                  o)  Multi-cpu stuff:                          o)  Find out which actual CPUs implement the rev2 ISA!
90                          +)  SGI's NUMA architecture. Study                          o)  DROTR32 and similar MIPS64 rev 2 instructions,
91                                  x)  Linux sources                              which have a rotation bit which differs from
92                                  x)  SGI's specs on NUMA address space                              previous ISAs.
93                          +)  Ultrix?  NetBSD doesn't do SMP on MIPS yet :-(                          o)  EI and DI instructions for MIPS64/32 rev 2.
94                          +)  Own experiments with ycx2.                              NOTE: These are _NOT_ the same as for R5900!
95                    x) _MAYBE_ TX79 and R5900 actually differ in their
96          Emulation of specific machines and devices:                     opcodes? Check this carefully!
97                  o)  Clean up stuff to make it possible to emulate multiple          o)  Dyntrans: Count register updates are probably not 100% correct yet.
98                      (different) machines simultaneously.          o)  Refactor code for performance and readability/maintainability.
99                  o)  Use same clock for all emulations and machines.          o)  (Re)implement 128-bit loads/stores for R5900.
100                  o)  Clean up the device stuff (registering of devices etc)          o)  R4000 and others:
101                  o)  Various SCSI and IDE controllers                  x)  watchhi/watchlo exceptions, and other exception
102                  o)  PS/2-style keyboard controller (for several machines)                      handling details
103                  o)  Generic busses;          o)  R10000 and others:  (R12000, R14000 ?)
104                          x)  PCI:  i/o and interrupts                  x)  The code before the line
105                          x)  QBus-22 (DECsystem 5500, 5400?)                          /*  reg[COP0_PAGEMASK] = cpu->cd.mips.coproc[0]->tlbs[0].mask & PAGEMASK_MASK;  */
106                  o)  DECstations (pmax):                      in cpu_mips.c is not correct for R10000 according to
107                          x)  ioasic                      Lemote's Godson patches for GXemul. TODO: Go through all
108                          x)  framebuffers:                      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
109                                  +)  better cursor support, overlays?,                      and make sure everything works with R10000.
110                                  +)  2D/3D acceleration, PX[G]                      Then test with OpenBSD/sgi?
111                          x)  status words / control words, make this more                  x)  Entry LO mask (as above).
112                                  portable/cleaner                  x)  memory space, exceptions, ...
113                          x)  scsi controller(s): sii, DMA for asc                  x)  use cop0 framemask for tlb lookups
114                          x)  serial controllers: ssc, scc (and more work on dc?)                      (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)
115                          x)  nvram on decstation 5000/125:  when using X11,  
116                                  set console=g or similar  SuperH:
117                          x)  DECstation 5840? "xbi-based SMP"          x)  SH4 interrupt controller:
118                  o)  SGI and ARC machines (sgimips, arc):                  x)  MASKING should be possible!
119                          x)  IP32 ("O2"): (Lots of stuff)          x)  SH4 DMA (0xffa00000)
120                                  +)  mec (ethernet)          x)  SH4 UBC (0xff200000)
121                                  +)  pci          x)  SH4 timers are going too fast!
122                                  +)  ahc (scsi)          x)  Store queues can copy 32 bytes at a time, there's no need to
123                                  +)  ps2 kbd              copy individual 32-bit words. (Performance improvement.)
124                                  +)  memory controller          x)  SH4 BSC (Bus State Controller)
125                                  +)  framebuffer/graphics          x)  Instruction tracing should include symbols for branch targets,
126                                  +)  caches              and so on, to make the output more human readable.
127                          x)  more ARCBIOS stuff          x)  SH3-specific devices: Pretty much everything!
128                          x)  Memory/interrupt controllers          x)  NetBSD/evbsh3, mmeye, hpcsh! Linux?
129                          x)  IP30 (Linux with graphics support?)          x)  Replace pc-relative loads with immediate load, if within the
130                          x)  SMP / NUMA?  (SGI and various ARC machines)              same page. (Similar to the same optimization for ARM.)
131                  o)  Playstation 2:          x)  Floating point speed!
132                          Hardware:  OHCI usb controller, keyboard, ...          x)  Floating point exception correctness.
133                  o)  Cobalt:  PCI and interrupt system, ethernet,          x)  Think carefully about how to implement SH5/SH64 (for evbsh5).
134                          harddisk controller(s)  
135                  o)  Less interesting platforms:  Landisk SH4:
136                          o)  newsmips:          x)  When NetBSD/landisk 4.0 and OpenBSD/landisk 4.1 have been
137                                  o)  NetBSD/newsmips, get it to detect a "real"              released, test to see if they work. (If so, update documentation,
138                                      model, right now everything is 100% bogus              guestos + index, and set stable=1 in machine_landisk.c.)
139                          o)  mipsco? (NetBSD)  
140                          o)  wgrisc? (big endian R3000, in OpenBSD's attic)  Dreamcast:
141                          o)  other embedded / evaluation MIPS boards          x)  G2 DMA
142                          o)  Playstation 1? R3000A. Weird hardware?          x)  LAN adapter (dev_mb8696x.c).  NetBSD root-on-nfs.
143                                  No FPU, but something as coproc 2.          x)  PVR:  Lots of stuff. See dev_pvr.c.
144                          o)  Nintendo 64, http://www.nintendo.com/systems/n64/n64_specs.jsp          x)  Better GDROM support
145                                  (R4300, 4MB RAM, really weird memory map)          x)  Modem
146                  o)  non-MIPS          x)  PCI bridge/bus?
147            x)  Maple bus:
148          File/disk handling:                  x)  Correct controller input
149                  o)  More than one type of disk in a machine (say, IDE + FLOPPY,                  x)  Mouse input
150                      or SCSI + IDE); how to handle this nicely?          x)  Software emulation of BIOS calls:
151                  o)  Read function argument count and types from binaries? (ELF?)                  x)  GD-ROM emulation: Use the GDROM device.
152                  o)  ELF: separate LE/BE (MIPS instruction format) from LSB/MSB                  x)  Use the VGA font as a fake ROM font. (Better than
153                          (ELF structure format)?                      nothing.)
154                  o)  Better handling of tape files          x)  Make as many as possible of the KOS examples run!
155            x)  More homebrew demos/games.
156          Userland ABI emulation:          x)  SPU: Sound emulation (ARM cpu).
157                  o)  see src/useremul.c          x)  VME processor emulation? "(Sanyo LC8670 "Potato")" according to
158                Wikipedia, LC86K87 according to Comstedt's page. See
159          Terminal based interactive debugger:              http://www.maushammer.com/vmu.html for a good description of
160                  o)  see src/debugger.c              the differences between LC86104C and the one used in the VME.
161    
162          GDB interface? (Maybe not necessary; the built-in debugger feels  Alpha:
163          more useful.)          x)  OSF1 PALcode, Virtual memory support.
164            x)  PALcode replacement! PAL1E etc opcodes...?
165          GUI, interactive debugger?  GTK+?  (The GUI _must be optional_!)          x)  Interrupt/exception/trap handling.
166                  o)  Breakpoints (complex expressions? combinations of register          x)  Floating point exception correctness.
167                          states, memory accesses and so on)          x)  More work on bootup memory and register contents.
168                  o)  Instruction trace          x)  More Alpha machine types, so it could work with
169                  o)  Disassembly of RAM (_NOT_ the same as instruction trace)              OpenBSD, FreeBSD, and Linux too?
170                  o)  Function call trace  
171                  o)  Inspection of CPU registers/state, coprocessor  SPARC (both the ISA and the machines):
172                          registers/state, any device registers/state/contents          o)  Implement Adress space identifiers; load/stores etc.
173                          o)  Framebuffers in windows / tabs.          o)  Exception/trap/interrupt handling.
174                          o)  Contents of RAM          o)  Save/restore register windows etc! Both v9 and pre-v9!
175                  o)  "Start new emulation" should allow amount of          o)  Finish the subcc and addcc flag computation code.
176                          RAM and nr of cpus to easily be specified.          o)  Add more registers (floating point, control regs etc)
177                          Multiple simultaneous machines should be possible.          o)  Disassemly of some more instructions?
178                  o)  Disk images.          o)  Are sll etc 32-bit sign-extending or zero-extending?
179            o)  Floating point exception correctness.
180          Regression tests:          o)  SPARC v8, v7 etc?
181                  o)  see tests/          o)  More machine modes and devices.
182    
183          Save state of the whole emulated machine, to be able to load it back  Debugger:
184                  in later?  (Memory, all device's states, all registers and          o)  How does SMP debugging work? Does it simply use "threads"?
185                  so on.  Like taking a snapshot. (SimOS seems to do this,                  What if the guest OS (running on an emulated SMP machine)
186                  according to its website.))                  has a usertask running, with userland threads?
187            o)  Try to make the debugger more modular and, if possible, reentrant!
188          Better X-windows functionality:          o)  Remove the emul command? (But show network info if showing
189                  o)  CLEAN UP the ugly event code                  machines?)
190                  o)  Mouse clicks can be "missed" in the current system; this is          o)  Evaluate expressions within []? That would allow stuff like
191                      not good. They should be put on a stack of some kind.                  cpu[x] where x is an expression.
192                  o)  More 2D and 3D framebuffer acceleration.          o)  Settings:
193                  o)  Non-resizable windows?  Or choose scaledown depending                  x)  Special handlers for Write!
194                          on size (and center the image, with a black border).                          +)  MIPS coproc regs
195                  o)  Different scaledown on different windows?                          +)  Alpha/MIPS/SPARC zero registers
196                  o)  Switch scaledown during runtime? (Ala CTRL-ALT-plus/minus)                          +)  x86 64/32/16-bit registers
197                  o)  Keyboard and mouse events:                  x)  Value formatter for resulting output.
198                          x)  Do this for more machines than just DECstation          o)  see src/debugger.c for more
199                          x)  more X11 cursor keycodes  
200                          x)  Keys like CTRL, ALT, SHIFT do not get through  POWER/PowerPC:
201                              by themselves (these are necessary for example          x)  Fix DECR timer speed, so it matches the host.
202                              to change the font of an xterm in X in the          x)  NetBSD/prep 3.x triggers a possible bug in the emulator:
203                              emulator)              <wdc_exec_command(0xd005e514,0xd60cdd30,0,8,..)>
204                  o)  Generalize the framebuffer stuff by moving _ALL_ X11                <ata_get_xfer(0,0xd60cdd30,0,8,..)>
205                          specific code to src/x11.c!                  <0x26c550(&ata_xfer_pool,2,0,8,..)>
206                    <0x35c71c(0x3f27000,0,52,8,..)>
207          Statistics:  (this could be interesting)                <ata_exec_xfer(0xd005e4c8,0x3f27000,0,13,..)>
208                  o)  Save to file and show graphics. It should be possible to                  <atastart(0xd005e4c8,0x3f27000,0,13,..)>
209                      run gxemul after a simulation to just show the graphics,                    <__wdccommand_start(0xd005e4c8,0x3f27000,0,13,..)>
210                      or convert to a .ppm or .tga or similar.                      <bsw1(&prep_isa_io_space_tag,0x800001f6,0,176,..)>
211                  o)  memory accesses (to measure cache efficiency and                  [ wdc: write to SDH: 0xb0 (sectorsize 2, lba=1, drive 1, head 0) ]
212                          page coloring efficiency)                      <wdcwait(0xd005e4c8,72,64,0xbb8,..)>
213                  o)  nr of simultaneous ASIDs in use in the TLB, for MIPS                        <0x198120(0xd005e4c8,72,64,0xbb8,..)>
214                  o)  percentage of time spent in different "states", such as                          <bsr1(&prep_isa_io_space_tag,0,0,0xbb8,..)>
215                      running userland code, kernel code, or idling (for CPUs                          <delay(100,0,0,0xbb8,..)>
216                      that have such an instruction, or whenever the PC is              Note: <bsr1(&prep_isa_io_space_tag,0,0,0xbb8,..)>
217                      inside a specific idle-function (address range)).          x)  PPC optimizations; instr combs
218                      Possible additional state (for example on R3000): caches          x)  64-bit stuff: either Linux on G5, or perhaps some hobbyist
219                      disabled.                  version of AIX? (if there exists such a thing)
220                  o)  position of read/write on (SCSI) disks          x)  macppc: adb controller; keyboard (for framebuffer mode)
221            x)  make OpenBSD/macppc work (PCI controller stuff)
222            x)  Floating point exception correctness.
223            x)  Alignment exceptions.
224    
225    PReP:
226            x)  Clock time! ("Bad battery blah blah")
227    
228    Algor:
229            o)  Other models than the P5064?
230            o)  PCI interrupts... needed for stuff like the tlp NIC?
231    
232    BeBox:
233            o)  Interrupts. There seems to be a problem with WDC interrupts
234                "after a short while", although a few interrupts get through?
235            o)  Perhaps find a copy of BeOS and try it?
236    
237    HPCmips:
238            x)  Mouse/pad support! :)
239            x)  A NIC? (As a PCMCIA device?)
240    
241    AVR:
242            o)  Everything.
243    
244    ARM:
245            o)  See netwinder_reset() in NetBSD; the current "an internal error
246                occured" message after reboot/halt is too ugly.
247            o)  ARM "wait"-like instruction?
248            o)  try to get netbsd/evbarm 3.x or 4.x running (iq80321)
249            o)  make the xscale counter registers (ccnt) work
250            o)  make the ata controller usable for FreeBSD!
251            o)  Zaurus emulation:
252                    x)  OpenBSD/zaurus
253                    x)  NetBSD/zaurus? See the following URL:
254                        http://mail-index.netbsd.org/port-arm/2006/11/19/0000.html
255            o)  Debian/cats crashes because of unimplemented coproc stuff.
256                fix this?
257    
258    Test machines:
259            o)  dev_fb block fill and copy
260            o)  dev_fb draw characters (from the built-in font)?
261            o)  dev_fb input device? mouse pointer coordinates and buttons
262                    (allow changes in these to cause interrupts as well?)
263            o)  Redefine the halt() function so that it stops "sometimes
264                soon", i.e. usage in demo code should be:
265                    for (;;) {
266                            halt();
267                    }
268    
269    Better CD Image file support:
270            x)  Support CD formats that contain more than 1 track, e.g.
271                CDI files (?). These can then contain a mixture of e.g. sound
272                and data tracks, and booting from an ISO filesystem path
273                would boot from [by default] the first data track.
274                (This would make sense for e.g. Dreamcast CD images, or
275                possibly other live-CD formats.)
276    
277    Networking:
278            x)  Redesign of the networking subsystem, at least the NAT translation
279                    part. The current way of allowing raw ethernet frames to be
280                    transfered to/from the emulator via UDP should probably be
281                    extended to allow the frames to be transmitted other ways as
282                    well.
283            x)  Also adding support for connecting ttys (either to xterms, or to
284                    pipes/sockets etc, or even to PPP->NAT or SLIP->NAT :-).
285            x)  Documentation updates (!) are very important, making it easier to
286                    use the (already existing) network emulation features.
287            x)  Fix performance problems caused by only allowing a
288                single TCP packet to be unacked.
289            x)  Don't hardcode offsets into packets!
290            x)  Test with lower than 100 max tcp/udp connections,
291                to make sure that reuse works!
292            x)  Make OpenBSD work better as a guest OS!
293            x)  DHCP? Debian doesn't actually send DHCP packets, even
294                    though it claims to? So it is hard to test.
295            x)  Multiple networks per emulation, and let different
296                NICs in machines connect to different networks.
297            x)  Support VDE (vde.sf.net)? Easiest/cleanest (before a
298                redesign of the network framework has been done) is
299                probably to connect it using the current (udp) solution.
300            x)  Allow SLIP connections, possibly PPP, in addition to
301                ethernet?
302    
303    Cache simulation:
304            o)  Command line flags for:
305                    o)  CPU endianness?
306                    o)  Cache sizes? (multiple levels)
307            o)  Separate from the CPU concept, so that multi-core CPUs sharing
308                e.g. a L2 cache can be simulated (?)
309            o)  Instruction cache emulation is easiest (if separate from the
310                data cache); similar hack as the S;I; hack in cpu_dyntrans.c.
311                NOTE: if the architecture has a delay slot, then an instruction
312                slot can actually be executed as 2 instructions.
313            o)  Data cache emulation = harder; each arch's load/store routines
314                must include support? running one instruction at a time and
315                having a cpu-dependant lookup function for each instruction
316                is another option (easier to implement, but very very slow).
317    
318    Documentation:
319            x)  Note about sandboxing/security:
320                    Not all emulated instructions fail in the way they would
321                    do on real hardware (e.g. a userspace program writing to
322                    a system register might work in GXemul, but it would
323                    fail on real hardware).  Sandbox = contain from the
324                    host OS. But the emulated programs will run "less
325                    securely".
326            x)  Try NetBSD/arc 4.x! (It seems to work with disk images!)
327            x)  NetBSD/pmax 4 install instructions: xterm instead of vt100!
328            x)  BETTER DEVICE EXAMPLES!
329                    o)  Move away from technical.html to somewhere new.
330                    o)  DEVICE_TICK
331                    o)  Implement example devices using interrupts, dyntrans
332                        memory access, etc.?
333            x)  Document the dyntrans core?
334            x)  Rewrite the section about experimental devices, after the
335                framebuffer acceleration has been implemented, and demos
336                written. (Symbolic names instead of numbers; example
337                use cases, etc. Mention demo files that use the various
338                features?)
339            x)  "a very simple linear framebuffer device (for graphics output)"
340                under "which machines does gxemul emulate" ==> better
341                description?
342            x)  Better description on how to set up a cross compiler?
343                Example for MIPS64.
344            o)  Automagic documentation generation?
345                    x)  machines, cpus, devices.
346                    x)  REMEMBER that several machines/devices can be in
347                            the same source file!
348            o)  Try to rewrite the install instructions for those machines
349                that use 3MAX into using CATS or hpcmips? (To remove the need
350                to use a raw ffs partition, using up all of the disk image.)
351    
352    More generic out_of_memory error reporting, and check everywhere!
353            Causes: OpenBSD has low default limits for normal users.
354                    Host is 32-bit? (32-bit hosts are limited to 4 GB or less
355                    of userspace memory.)
356                    You are actually low on RAM. (As trivial as this might sound,
357                    Unix systems usually allow processes to allocate virtual
358                    memory beyond the amount of RAM in the machine.)
359    
360    The Device subsystem:
361            x)  allow devices to be moved and/or changed in size (down to a
362                minimum size, etc, or up to a max size); if there is a collision,
363                return false. It is up to the caller to handle this situation!
364            x)  NOTE: Translations must be invalidated, both for
365                registering new devices, and for moving existing ones.
366                cpu->invalidate translation caches, for all CPUs that
367                are connected to a specific memory.
368            x)  keep track of interrupts and busses? actually, allowing any device
369                to be a bus might be a nice idea.
370            x)  turn interrupt controllers into devices? :-)
371            x)  refactor various clocks/nvram/cmos into one device?
372    
373    PCI:
374            x)  Pretty much everything related to runtime configuration, device
375                slots, interrupts, etc must be redesigned/cleaned up. The current
376                code is very hardcoded and ugly.
377            o)  Allow cards to be added/removed during runtime more easily.
378            o)  Allow cards to be enabled/disabled (i/o ports, etc, like
379                NetBSD needs for disk controller detection).
380            o)  Allow devices to be moved in memory during runtime.
381            o)  Interrupts per PCI slot, etc. (A-D).
382            o)  PCI interrupt controller logic... very hard to get right,
383                because these differ a lot from one machine to the next.
384            x)  last write was ffffffff ==> fix this, it should be used
385                together with a mask to get the correct bits. also, not ALL
386                bits are size bits! (lowest 4 vs lowest 2?)
387            x)  add support for address fixups
388            x)  generalize the interrupt routing stuff (lines etc)
389    
390    Clocks and timers:
391            x)  Fix the PowerPC DECR interrupt speed! (MacPPC and PReP speed, etc.)
392            x)  DON'T HARDCODE 100 HZ IN cpu_mips_coproc.c!
393            x)  Test the 8253? Right now it doesn't seem to be used?
394            x)  NetWinder timeofday is incorrect!
395            x)  Cobalt TOD is incorrect!
396            x)  Go through all other machines, one by one, and fix them.
397    
398    Config file parser:
399            o)  Rewrite it from scratch!
400            o)  Usage of any expression available through the debugger
401            o)  Allow interrupt controllers to be added! and interrupts
402                to be used in more ways than before
403            o)  Support for running debugger commands (like the -c
404                command line option)
405    
406    Floating point layer:
407            o)  make it common enough to be used by _all_ emulation modes
408            o)  implement correct error/exception handling and rounding modes
409            o)  implement more helper functions (i.e. add, sub, mul...)
410            o)  non-IEEE modes (i.e. x86)?
411    
412    Userland emulation:
413            x)  Dynamic linking!
414            x)  Lots of stuff; freebsd, netbsd, linux, ... syscalls.
415            x)  Initial register/stack contents (environment, command line args).
416            x)  Return value (from main).
417            x)  mmap emulation layer
418            x)  errno emulation layer
419            x)  struct conversions for may syscalls
420    
421    Sound:
422            x)  generic sound framework
423            x)  add one or more sound cards as devices; add a testmachine
424                sound card first?
425            x)  Dreamcast sound? Generic PCI sound cards?
426    
427    ASC SCSI controller:
428            x)  NetBSD/arc 2.0 uses the ASC controller in a way which GXemul
429                cannot yet handle. (NetBSD 1.6.2 works ok.) (Possibly a problem
430                in NetBSD itself, http://mail-index.netbsd.org/source-changes/
431                2005/11/06/0024.html suggests that.)
432                NetBSD 4.x seems to work? :)
433    
434    Caches / memory hierarchies: (this is mostly MIPS-specific)
435            o)  src/memory*.c: Implement correct cache emulation for
436                all CPU types. (currently only R2000/R3000 is implemented)
437                (per CPU, multiple levels should be possible, associativity etc!)
438            o)  R2000/R3000 isn't _100%_ correct, just almost correct :)
439            o)  Move the -S (fill mem with random) functionality into the
440                memory.c subsystem, not machine.c or wherever it is now
441            o)  ECC stuff, simulation of memory errors?  (Machine dependent)
442            o)  More than 4GB of emulated RAM, when run on a 32-bit host?
443                (using manual swap-out of blocks to disk, ugly)
444            o)  A global command line option should be used to turn
445                cache emulation on or off. When off, caches should be
446                faked like they are right now. When on, caches and
447                memory latencies should be emulated as correctly as
448                possible.
449    
450    File/disk/symbol handling:
451            o)  Make sure that disks can be added/removed during runtime!
452                (Perhaps this needs a reasonably large re-write.)
453            o)  Remove some of the complexity in file format guessing, for
454                    Ultrix kernels that are actually disk images?
455            o)  Better handling of tape files      
456            o)  Read function argument count and types from binaries? (ELF?)
457            o)  Better demangling of C++ names. Note: GNU's C++ differs from e.g.
458                Microsoft's C++, so multiple schemes must be possible. See
459                URL at top of src/symbol_demangle.c for more info.
460    
461    Userland ABI emulation:
462            o)  see src/useremul.c
463    
464    Better framebuffer and X-windows functionality:
465            o)  Generalize the update_x1y1x2y2 stuff to an extend-region()
466                function...
467            o)  -Yx sometimes causes crashes.
468            o)  Simple device access to framebuffer_blockcopyfill() etc,
469                and text output (using the built-in fonts), for dev_fb.
470            o)  CLEAN UP the ugly event code
471            o)  Mouse clicks can be "missed" in the current system; this is
472                not good. They should be put on a stack of some kind.
473            o)  More 2D and 3D framebuffer acceleration.
474            o)  Non-resizable windows?  Or choose scaledown depending
475                    on size (and center the image, with a black border).
476            o)  Different scaledown on different windows?
477            o)  Non-integral scale-up? (E.g. 640x480 -> 1024x768)
478            o)  Switch scaledown during runtime? (Ala CTRL-ALT-plus/minus)
479            o)  Bug reported by Elijah Rutschman on MacOS with weird
480                keys (F5 = cursor down?).
481            o)  Keyboard and mouse events:
482                    x)  Do this for more machines than just DECstation
483                    x)  more X11 cursor keycodes
484                    x)  Keys like CTRL, ALT, SHIFT do not get through
485                        by themselves (these are necessary for example
486                        to change the font of an xterm in X in the
487                        emulator)
488            o)  Generalize the framebuffer stuff by moving _ALL_ X11
489                    specific code to src/x11.c!
490    

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