/[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 12 by dpavlin, Mon Oct 8 16:18:38 2007 UTC revision 40 by dpavlin, Mon Oct 8 16:22:11 2007 UTC
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1  $Id: TODO,v 1.166 2005/08/16 05:44:33 debug Exp $  $Id: TODO,v 1.489 2007/05/01 04:05:06 debug Exp $
2    
3  ===============================================================================  --------------------------------------------
4    
5  High priority stuff:  Testing for the next release (0.4.5.1):
6    
7    TEST DISK OVERLAY IMAGES
8  MIPS bintrans:  TEST LANDISK/SUPERH EMULATION MODES
9          x)  call/return address cache?  REGRESSION TESTS FOR ALL OTHER SUPPORTED GUEST OSES
10    
11  dyntrans:  # NetBSD/pmax 3.1 or 1.6.2      OK
12          x)  memory write protection for ARM, but NOT for Alpha (because  # NetBSD/arc 1.6.2              OK
13                  it has the IMB instruction... hm)  # NetBSD/hpcmips 3.1            OK
14    # NetBSD/cobalt 3.1             OK
15          x)  call/return address cache  # NetBSD/evbmips 3.1            OK
16    # NetBSD/algor 3.1              OK
17          x)  instr_call sequence analysis support? (Useful for  # NetBSD/sgimips 3.1            OK
18                  handtuning combinations.)  # NetBSD/cats 3.1               OK
19    # NetBSD/evbarm 2.1             OK
20          x)  opcode statistics support?  # NetBSD/netwinder 3.1          OK
21                  TODO: is instr_call statistics enough?  # NetBSD/prep 2.1               OK
22    # NetBSD/macppc 3.1             OK
23          x)  support for archs that allow transparent unaligned load/stores  # NetBSD/dreamcast 3.1 MD       OK
24    # NetBSD/dreamcast 3.1 LiveCD   OK
25          x)  SMP: detect when an instruction such as ll/sc or cas is used,  # Linux/dreamcast Live CD       OK
26              and "synchronize" approximately the number of executed instructions  # OpenBSD/pmax 2.8-BETA         not tested because of lack of time
27              (or cycles) across all CPUs.  # OpenBSD/cats 4.0              OK
28    # OpenBSD/landisk 4.1           OK
29          x)  support for variable-length instructions (x86, m68k, ...)  # Ultrix/RISC 4.5               OK
30                  Perhaps:  don't increase the next_ic between every  # Sprite for DECstation         OK
31                  instruction, but let each instruction's handler do  # Debian GNU/Linux for pmax     not tested because of lack of time
32                  that for itself.  
33                  Problem: what about instructions crossing a (virtual)  Optional:
34                          page boundary? They cannot be translated once  # OpenBSD/sgi                   FAILED to boot after setup (as expected)
35                          and for all :( and must be interpreted slowly!  
36    --------------------------------------------
37          x)  support for THUMB or MIPS16  (arm, mips)  
38    Some things, in totally random order, that I'd like to fix:
39          x)  support for Delay slots!  (mips, sparc, hppa)  (Some items in this list are possibly out-of-date by now.)
40    
41          x)  Alpha: hahaha, zapnot and inserts/extracts don't  Dyntrans:
42              compile into very nice code :-|  fix this          x)  Instruction combination collisions? How to avoid easily...
43            x)  Think about how to do both SHmedia and SHcompact in a reasonable
44          x)  64-bit virtual memory translation tables (PPC, etc)              way! (Or AMD64 long/protected/real, for that matter.)
45            x)  68K emulation; think about how to do variable instruction
46          x)  x86: convert to dyntrans. LOTS of stuff to consider.              lengths across page boundaries.
47            x)  Dyntrans with valgrind-inspired memory checker. (In memory_rw,
48                it would be reasonably simple to add; in each individual fast
49  ===============================================================================              load/store routine = a lot more work, and it would become
50                kludgy very fast.)
51  Lower priority, but still important:          x)  Dyntrans with SMP... lots of work to be done here.
52            x)  Dyntrans with cache emulation... lots of work here as well.
53          Redesign the entire "mainbus" concept:          x)  Remove the concept of base RAM completely; it would be more
54                  o)  Easily configurable interrupt routing in SMP systems.              generic to allow RAM devices to be used "anywhere".
55                  o)  Specific clock/bus speeds, cpu speeds etc.          o)  dev_mp doesn't work well with dyntrans yet
56                  o)  Synchronization over network?          o)  In general, IPIs, CAS, LL/SC etc must be made to work with dyntrans
57            x)  Redesign/rethink the delay slot mechanism used for e.g. MIPS,
58          Caches / memory hierarchies: (this is mostly MIPS-specific)                  so that it caches a translation (that is, an instruction
59                  o)  MIPS coproc.c: bits in config registers should reflect                  word and the instr_call it was translated to the last
60                      correct cache sizes for _all_ CPU types. (currently only                  time), so that it doesn't need to do slow
61                      implemented for R4000, R1x000, and a few others)                  to_be_translated for each end of page?
62                  o)  src/memory*.c: Implement correct cache emulation for          x)  Program Counter statistics:
63                      all CPU types. (currently only R2000/R3000 is implemented)                  Per machine? What about SMP? All data to the same file?
64                      (per CPU, multiple levels should be possible,                  A debugger command should be possible to use to enable/
65                      associativity etc!)                  disable statistics gathering.
66                  o)  R2000/R3000 isn't _100%_ correct, just almost correct :)                  Configuration file option!
67                  o)  Move the -S (fill mem with random) functionality into the          x)  Breakpoints:
68                      memory.c subsystem, not machine.c or wherever it is now                  o) Physical vs virtual addresses!
69                  o)  ECC stuff, simulation of memory errors?  (Machine dependant)                  o) 32-bit vs 64-bit sign extension for MIPS, and others?
70                  o)  More than 4GB of emulated RAM, when run on a 32-bit host?          x)  INVALIDATION should cause translations in _all_ cpus to be
71                      (using manual swap-out of blocks to disk, ugly)              invalidated, e.g. on a write to a write-protected page
72                  o)  A global command line option should be used to turn              (containing code)
73                      cache emulation on or off. When off, caches should be          x)  16-bit encodings? (MIPS16, ARM Thumb, 32-bit SH on SH64)
74                      faked like they are right now. When on, caches and          x)  Lots of other stuff: see src/cpus/README_DYNTRANS
75                      memory latencies should be emulated as correctly as          x)  Native code generation backends:
76                      possible.                  o)  think carefully about this.
77                    o)  simple syntax for emitting opcodes; backend implementation
78          Network layer:                      must be optional, so I don't have to write more code
79                  o)  Multiple networks per emulation, and let different                      than necessary. after all, the non-native (C) code should
80                      NICs in machines connect to different networks.                      always work.
81                  o)  many other issues: see src/net.c                  o)  convert into native code only after an entire
82                            block has been translated? probably best.
83          MIPS CPU emulation:                  o)  the "almost native" opcodes may be rearranged,
84                  o)  i386 bintrans backend: movn etc, slt[u] for                      "peep-hole optimized", etc. and then as a separate step
85                          64-bit mode, 64-bit shifts etc                      this list of almost native opcodes is written out
86                  o)  Instructions:                      as native code.
87                          o)  All ISAs:                  o)  think about delay slots at the end of a block!
88                                  o)  Floating point exception handling, and                  o)  x86/amd64 code generator can be very similar... perhaps
89                                          add more instructions.                  o)  NOTE that generation is per _ABI_, not per host arch!
90                                  o)  Finish the MIPS16 translator, and test it!                      the configure script must detect ABI!!!
91                                  o)  MIPS ISA I, II, III, IV                  o)  branches to already translated code blocks can
92                                  o)  MIPS V (SIMD vector stuff?)                          link the blocks together
93                                  o)  MDMX  (MIPS Digital Media Extension)                  o)  load/store are the most important to optimize
94                                  o)  MIPS 3D  
95                                  o)  MIPS MT (Multi-thread stuff) (What's this?)  Simple Valgrind-like checks?
96                          o)  Warn about mis-used bit fields (ie bits that          o)  Mark every address with bits which tell whether or not the address
97                              should be all zeroes, warn about if they are not)!              has been written to.
98                              Both for coprocessor registers and for instruction          o)  What should happen when programs are loaded?  Text/data, bss (zero
99                              opcodes.              filled). But stack space and heap is uninitialized.
100                          o)  the special2 stuff is a mess right now          o)  Uninitialized local variables:
101                          o)  warn and/or cause exceptions for unimplemented                  A load from a place on the stack which has not previously
102                              instructions (depending on CPU type)                  been stored to => warning. Increasing the stack pointer using
103                  o)  R2000/R3000:                  any available means should reset the memory to uninitialized.
104                          x)  R3000 "tri-byte stores". (What's this?)          o)  If calls to malloc() and free() can be intercepted:
105                  o)  R4000 and others:                  o)  Access to a memory area after free() => warning.
106                          x)  watchhi/watchlo exceptions, and other exception                  o)  Memory returned by malloc() is marked as not-initialized.
107                              handling details                  o)  Non-passive, but good to have: Change the argument
108                  o)  R10000 and others:  (R12000, R14000 ?)                      given to malloc, to return a slightly larger memory
109                          x)  memory space, exceptions, ...                      area, i.e.  margin_before + size + margin_after,
110                          x)  use cop0 framemask for tlb lookups                      and return the pointer  + margin_before.
111                              (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)                      Any access to the margin_before or _after space results
112                  o)  Implement load delays?  Warnings on interlocks.                      in warnings. (free() must be modified to free the
113                  o)  Implement all coprocessor 0 bits / functions.                      actually allocated address.)
114                          x)  coproc 0 selectors! (R4000 ?)  
115                  o)  R4300 (nintendo64, no mmu?), R5900 (playstation2, weird  MIPS:
116                          TLB/cache? 128-bit GPRs, new instructions),          o)  Nicer MIPS status bits in register dumps.
117                          4K (note: NOT R4000), 5K (note: NOT R5000),          o)  Alignment exceptions.
118                          R6000 (ISA II), R8000          o)  Floating point exception correctness.
119                  o)  Multi-cpu stuff:          o)  Fix this? Triggered by NetBSD/sgimips? Hm:
120                          +)  Interrupt routing (ie devices vs mainbus, or                  to_be_translated(): TODO: unimplemented instruction:
121                              connect each device to a fixed cpu)                  000000000065102c: 00200800 (d)  rot_00  at,zr,0
122                          +)  SGI's NUMA architecture. Study          o)  Some more work on opcodes.
123                                  x)  Linux sources                  x) MIPS64 revision 2.
124                                  x)  SGI's specs on NUMA address space                          o)  Find out which actual CPUs implement the rev2 ISA!
125                          +)  Ultrix?  NetBSD doesn't do SMP on MIPS yet :-(                          o)  DROTR32 and similar MIPS64 rev 2 instructions,
126                          +)  Own experiments with ycx2.                              which have a rotation bit which differs from
127                                previous ISAs.
128          File/disk handling:                          o)  EI and DI instructions for MIPS64/32 rev 2.
129                  o)  Better handling of tape files                              NOTE: These are _NOT_ the same as for R5900!
130                    x) _MAYBE_ TX79 and R5900 actually differ in their
131          Debugger:                     opcodes? Check this carefully!
132                  o)  Read function argument count and types from binaries? (ELF?)          o)  Dyntrans: Count register updates are probably not 100% correct yet.
133                  o)  Demangle C++ names.          o)  Refactor code for performance and readability/maintainability.
134            o)  (Re)implement 128-bit loads/stores for R5900.
135          Userland ABI emulation:          o)  R4000 and others:
136                  o)  see src/useremul.c                  x)  watchhi/watchlo exceptions, and other exception
137                        handling details
138          Terminal based interactive debugger:          o)  R10000 and others:  (R12000, R14000 ?)
139                  o)  see src/debugger.c                  x)  The code before the line
140                            /*  reg[COP0_PAGEMASK] = cpu->cd.mips.coproc[0]->tlbs[0].mask & PAGEMASK_MASK;  */
141          Terminal/console stuff:                      in cpu_mips.c is not correct for R10000 according to
142                  o)  allow emulated serial ports to be connected to the outside                      Lemote's Godson patches for GXemul. TODO: Go through all
143                      world in a more generic way, or even to other emulated                      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
144                      machines(!)                      and make sure everything works with R10000.
145                        Then test with OpenBSD/sgi?
146          Regression tests.  (Needs to be totally rewritten, the old framework                  x)  Entry LO mask (as above).
147                  was removed because it was useless.)                  x)  memory space, exceptions, ...
148                    x)  use cop0 framemask for tlb lookups
149          Save state of the whole emulated machine, to be able to load it back                      (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)
150                  in later?  (Memory, all device's states, all registers and  
151                  so on.  Like taking a snapshot. (SimOS seems to do this,  SuperH:
152                  according to its website.))          x)  SH4 performance is VERY low when running user-space instructions,
153                because I actually simulate the 4-entry ITLB as being separate
154          Better X-windows functionality:              from the 64-entry DTLB. This is correct, but VERY slow. I need
155                  o)  CLEAN UP the ugly event code              to experiment with _not_ simulating it in too much detail.
156                  o)  Mouse clicks can be "missed" in the current system; this is          x)  SH4 interrupt controller:
157                      not good. They should be put on a stack of some kind.                  x)  MASKING should be possible!
158                  o)  More 2D and 3D framebuffer acceleration.          x)  SH4 DMA (0xffa00000)
159                  o)  Non-resizable windows?  Or choose scaledown depending          x)  SH4 UBC (0xff200000)
160                          on size (and center the image, with a black border).          x)  Store queues can copy 32 bytes at a time, there's no need to
161                  o)  Different scaledown on different windows?              copy individual 32-bit words. (Performance improvement.)
162                  o)  Switch scaledown during runtime? (Ala CTRL-ALT-plus/minus)          x)  SH4 BSC (Bus State Controller)
163                  o)  Keyboard and mouse events:          x)  Instruction tracing should include symbols for branch targets,
164                          x)  Do this for more machines than just DECstation              and so on, to make the output more human readable.
165                          x)  more X11 cursor keycodes          x)  SH3-specific devices: Pretty much everything!
166                          x)  Keys like CTRL, ALT, SHIFT do not get through          x)  NetBSD/evbsh3, mmeye, hpcsh! Linux?
167                              by themselves (these are necessary for example          x)  Replace pc-relative loads with immediate load, if within the
168                              to change the font of an xterm in X in the              same page. (Similar to the same optimization for ARM.)
169                              emulator)          x)  Floating point speed!
170                  o)  Generalize the framebuffer stuff by moving _ALL_ X11          x)  Floating point exception correctness.
171                          specific code to src/x11.c!          x)  NetBSD HEAD (as of April 2007) hangs during bootup, because it
172                turns on/off interrupts in an unfortunately synchronized way
173          Statistics:  (this could be interesting)              with dyntrans. This needs to be fixed.
174                  o)  Save to file and show graphics. It should be possible to          x)  Exceptions for unaligned load/stores. OpenBSD/landisk uses
175                      run gxemul after a simulation to just show the graphics,              this mechanism for its reboot code (machine_reset).
176                      or convert to a .ppm or .tga or similar.          x)  Think carefully about how to implement SH5/SH64 (for evbsh5).
177                  o)  memory accesses (to measure cache efficiency and  
178                          page coloring efficiency)  Landisk SH4:
179                  o)  nr of simultaneous ASIDs in use in the TLB, for MIPS          x)  When NetBSD/landisk 4.0 has been released, make sure it works
180                  o)  percentage of time spent in different "states", such as              in the emulator. (Update documentation, etc.)
181                      running userland code, kernel code, or idling (for CPUs  
182                      that have such an instruction, or whenever the PC is  Dreamcast:
183                      inside a specific idle-function (address range)).          x)  G2 DMA
184                      Possible additional state (for example on R3000): caches          x)  LAN adapter (dev_mb8696x.c).  NetBSD root-on-nfs.
185                      disabled.          x)  PVR:  Lots of stuff. See dev_pvr.c.
186                  o)  position of read/write on (SCSI) disks          x)  Better GDROM support
187            x)  Modem
188            x)  PCI bridge/bus?
189            x)  Maple bus:
190                    x)  Correct controller input
191                    x)  Mouse input
192            x)  Software emulation of BIOS calls:
193                    x)  GD-ROM emulation: Use the GDROM device.
194                    x)  Use the VGA font as a fake ROM font. (Better than
195                        nothing.)
196            x)  Make as many as possible of the KOS examples run!
197            x)  More homebrew demos/games.
198            x)  SPU: Sound emulation (ARM cpu).
199            x)  VME processor emulation? "(Sanyo LC8670 "Potato")" according to
200                Wikipedia, LC86K87 according to Comstedt's page. See
201                http://www.maushammer.com/vmu.html for a good description of
202                the differences between LC86104C and the one used in the VME.
203    
204    Alpha:
205            x)  OSF1 PALcode, Virtual memory support.
206            x)  PALcode replacement! PAL1E etc opcodes...?
207            x)  Interrupt/exception/trap handling.
208            x)  Floating point exception correctness.
209            x)  More work on bootup memory and register contents.
210            x)  More Alpha machine types, so it could work with
211                OpenBSD, FreeBSD, and Linux too?
212    
213    SPARC (both the ISA and the machines):
214            o)  Implement Adress space identifiers; load/stores etc.
215            o)  Exception/trap/interrupt handling.
216            o)  Save/restore register windows etc! Both v9 and pre-v9!
217            o)  Finish the subcc and addcc flag computation code.
218            o)  Add more registers (floating point, control regs etc)
219            o)  Disassemly of some more instructions?
220            o)  Are sll etc 32-bit sign-extending or zero-extending?
221            o)  Floating point exception correctness.
222            o)  SPARC v8, v7 etc?
223            o)  More machine modes and devices.
224    
225    Debugger:
226            o)  How does SMP debugging work? Does it simply use "threads"?
227                    What if the guest OS (running on an emulated SMP machine)
228                    has a usertask running, with userland threads?
229            o)  Try to make the debugger more modular and, if possible, reentrant!
230            o)  Remove the emul command? (But show network info if showing
231                    machines?)
232            o)  Evaluate expressions within []? That would allow stuff like
233                    cpu[x] where x is an expression.
234            o)  Settings:
235                    x)  Special handlers for Write!
236                            +)  MIPS coproc regs
237                            +)  Alpha/MIPS/SPARC zero registers
238                            +)  x86 64/32/16-bit registers
239                    x)  Value formatter for resulting output.
240            o)  see src/debugger.c for more
241    
242    POWER/PowerPC:
243            x)  Fix DECR timer speed, so it matches the host.
244            x)  NetBSD/prep 3.x triggers a possible bug in the emulator:
245                <wdc_exec_command(0xd005e514,0xd60cdd30,0,8,..)>
246                  <ata_get_xfer(0,0xd60cdd30,0,8,..)>
247                    <0x26c550(&ata_xfer_pool,2,0,8,..)>
248                    <0x35c71c(0x3f27000,0,52,8,..)>
249                  <ata_exec_xfer(0xd005e4c8,0x3f27000,0,13,..)>
250                    <atastart(0xd005e4c8,0x3f27000,0,13,..)>
251                      <__wdccommand_start(0xd005e4c8,0x3f27000,0,13,..)>
252                        <bsw1(&prep_isa_io_space_tag,0x800001f6,0,176,..)>
253                    [ wdc: write to SDH: 0xb0 (sectorsize 2, lba=1, drive 1, head 0) ]
254                        <wdcwait(0xd005e4c8,72,64,0xbb8,..)>
255                          <0x198120(0xd005e4c8,72,64,0xbb8,..)>
256                            <bsr1(&prep_isa_io_space_tag,0,0,0xbb8,..)>
257                            <delay(100,0,0,0xbb8,..)>
258                Note: <bsr1(&prep_isa_io_space_tag,0,0,0xbb8,..)>
259            x)  PPC optimizations; instr combs
260            x)  64-bit stuff: either Linux on G5, or perhaps some hobbyist
261                    version of AIX? (if there exists such a thing)
262            x)  macppc: adb controller; keyboard (for framebuffer mode)
263            x)  make OpenBSD/macppc work (PCI controller stuff)
264            x)  Floating point exception correctness.
265            x)  Alignment exceptions.
266    
267    PReP:
268            x)  Clock time! ("Bad battery blah blah")
269    
270    Algor:
271            o)  Other models than the P5064?
272            o)  PCI interrupts... needed for stuff like the tlp NIC?
273    
274    BeBox:
275            o)  Interrupts. There seems to be a problem with WDC interrupts
276                "after a short while", although a few interrupts get through?
277            o)  Perhaps find a copy of BeOS and try it?
278    
279    HPCmips:
280            x)  Mouse/pad support! :)
281            x)  A NIC? (As a PCMCIA device?)
282    
283    M88K:
284            o)  Everything. :)
285                    o)  More instruction disassembly!
286                    o)  Implement more instructions.
287                    o)  has-delay-slot (for debugging)
288                    o)  Find manuals!
289                    o)  MMU stuff
290                    o)  Exceptions
291                    o)  FPU
292                    o)  Control registers
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:
305                    x)  OpenBSD/zaurus
306                    x)  NetBSD/zaurus? See the following URL:
307                        http://mail-index.netbsd.org/port-arm/2006/11/19/0000.html
308            o)  Debian/cats crashes because of unimplemented coproc stuff.
309                fix this?
310    
311    Test machines:
312            o)  dev_fb block fill and copy
313            o)  dev_fb draw characters (from the built-in font)?
314            o)  dev_fb input device? mouse pointer coordinates and buttons
315                    (allow changes in these to cause interrupts as well?)
316            o)  Redefine the halt() function so that it stops "sometimes
317                soon", i.e. usage in demo code should be:
318                    for (;;) {
319                            halt();
320                    }
321    
322    Better CD Image file support:
323            x)  Support CD formats that contain more than 1 track, e.g.
324                CDI files (?). These can then contain a mixture of e.g. sound
325                and data tracks, and booting from an ISO filesystem path
326                would boot from [by default] the first data track.
327                (This would make sense for e.g. Dreamcast CD images, or
328                possibly other live-CD formats.)
329    
330    Networking:
331            x)  Redesign of the networking subsystem, at least the NAT translation
332                    part. The current way of allowing raw ethernet frames to be
333                    transfered to/from the emulator via UDP should probably be
334                    extended to allow the frames to be transmitted other ways as
335                    well.
336            x)  Also adding support for connecting ttys (either to xterms, or to
337                    pipes/sockets etc, or even to PPP->NAT or SLIP->NAT :-).
338            x)  Documentation updates (!) are very important, making it easier to
339                    use the (already existing) network emulation features.
340            x)  Fix performance problems caused by only allowing a
341                single TCP packet to be unacked.
342            x)  Don't hardcode offsets into packets!
343            x)  Test with lower than 100 max tcp/udp connections,
344                to make sure that reuse works!
345            x)  Make OpenBSD work better as a guest OS!
346            x)  DHCP? Debian doesn't actually send DHCP packets, even
347                    though it claims to? So it is hard to test.
348            x)  Multiple networks per emulation, and let different
349                NICs in machines connect to different networks.
350            x)  Support VDE (vde.sf.net)? Easiest/cleanest (before a
351                redesign of the network framework has been done) is
352                probably to connect it using the current (udp) solution.
353            x)  Allow SLIP connections, possibly PPP, in addition to
354                ethernet?
355    
356    Cache simulation:
357            o)  Command line flags for:
358                    o)  CPU endianness?
359                    o)  Cache sizes? (multiple levels)
360            o)  Separate from the CPU concept, so that multi-core CPUs sharing
361                e.g. a L2 cache can be simulated (?)
362            o)  Instruction cache emulation is easiest (if separate from the
363                data cache); similar hack as the S;I; hack in cpu_dyntrans.c.
364                NOTE: if the architecture has a delay slot, then an instruction
365                slot can actually be executed as 2 instructions.
366            o)  Data cache emulation = harder; each arch's load/store routines
367                must include support? running one instruction at a time and
368                having a cpu-dependant lookup function for each instruction
369                is another option (easier to implement, but very very slow).
370    
371    Documentation:
372            x)  Note about sandboxing/security:
373                    Not all emulated instructions fail in the way they would
374                    do on real hardware (e.g. a userspace program writing to
375                    a system register might work in GXemul, but it would
376                    fail on real hardware).  Sandbox = contain from the
377                    host OS. But the emulated programs will run "less
378                    securely".
379            x)  Try NetBSD/arc 4.x! (It seems to work with disk images!)
380            x)  NetBSD/pmax 4 install instructions: xterm instead of vt100!
381            x)  BETTER DEVICE EXAMPLES!
382                    o)  Move away from technical.html to somewhere new.
383                    o)  DEVICE_TICK
384                    o)  Implement example devices using interrupts, dyntrans
385                        memory access, etc.?
386            x)  Document the dyntrans core?
387            x)  Rewrite the section about experimental devices, after the
388                framebuffer acceleration has been implemented, and demos
389                written. (Symbolic names instead of numbers; example
390                use cases, etc. Mention demo files that use the various
391                features?)
392            x)  "a very simple linear framebuffer device (for graphics output)"
393                under "which machines does gxemul emulate" ==> better
394                description?
395            x)  Better description on how to set up a cross compiler?
396                Example for MIPS64.
397            o)  Automagic documentation generation?
398                    x)  machines, cpus, devices.
399                    x)  REMEMBER that several machines/devices can be in
400                            the same source file!
401            o)  Try to rewrite the install instructions for those machines
402                that use 3MAX into using CATS or hpcmips? (To remove the need
403                to use a raw ffs partition, using up all of the disk image.)
404    
405    More generic out_of_memory error reporting, and check everywhere!
406            Causes: OpenBSD has low default limits for normal users.
407                    Host is 32-bit? (32-bit hosts are limited to 4 GB or less
408                    of userspace memory.)
409                    You are actually low on RAM. (As trivial as this might sound,
410                    Unix systems usually allow processes to allocate virtual
411                    memory beyond the amount of RAM in the machine.)
412    
413    The Device subsystem:
414            x)  allow devices to be moved and/or changed in size (down to a
415                minimum size, etc, or up to a max size); if there is a collision,
416                return false. It is up to the caller to handle this situation!
417            x)  NOTE: Translations must be invalidated, both for
418                registering new devices, and for moving existing ones.
419                cpu->invalidate translation caches, for all CPUs that
420                are connected to a specific memory.
421            x)  keep track of interrupts and busses? actually, allowing any device
422                to be a bus might be a nice idea.
423            x)  turn interrupt controllers into devices? :-)
424            x)  refactor various clocks/nvram/cmos into one device?
425    
426    PCI:
427            x)  Pretty much everything related to runtime configuration, device
428                slots, interrupts, etc must be redesigned/cleaned up. The current
429                code is very hardcoded and ugly.
430            o)  Allow cards to be added/removed during runtime more easily.
431            o)  Allow cards to be enabled/disabled (i/o ports, etc, like
432                NetBSD needs for disk controller detection).
433            o)  Allow devices to be moved in memory during runtime.
434            o)  Interrupts per PCI slot, etc. (A-D).
435            o)  PCI interrupt controller logic... very hard to get right,
436                because these differ a lot from one machine to the next.
437            x)  last write was ffffffff ==> fix this, it should be used
438                together with a mask to get the correct bits. also, not ALL
439                bits are size bits! (lowest 4 vs lowest 2?)
440            x)  add support for address fixups
441            x)  generalize the interrupt routing stuff (lines etc)
442    
443    Clocks and timers:
444            x)  Fix the PowerPC DECR interrupt speed! (MacPPC and PReP speed, etc.)
445            x)  DON'T HARDCODE 100 HZ IN cpu_mips_coproc.c!
446            x)  Test the 8253? Right now it doesn't seem to be used?
447            x)  NetWinder timeofday is incorrect! It seems to be exactly
448                1 day ahead of actual time?
449            x)  Cobalt TOD is incorrect!
450            x)  Go through all other machines, one by one, and fix them.
451    
452    Config file parser:
453            o)  Rewrite it from scratch!
454            o)  Usage of any expression available through the debugger
455            o)  Allow interrupt controllers to be added! and interrupts
456                to be used in more ways than before
457            o)  Support for running debugger commands (like the -c
458                command line option)
459    
460    Floating point layer:
461            o)  make it common enough to be used by _all_ emulation modes
462            o)  implement correct error/exception handling and rounding modes
463            o)  implement more helper functions (i.e. add, sub, mul...)
464            o)  non-IEEE modes (i.e. x86)?
465    
466    Userland emulation:
467            x)  Dynamic linking!
468            x)  Lots of stuff; freebsd, netbsd, linux, ... syscalls.
469            x)  Initial register/stack contents (environment, command line args).
470            x)  Return value (from main).
471            x)  mmap emulation layer
472            x)  errno emulation layer
473            x)  struct conversions for may syscalls
474    
475    Sound:
476            x)  generic sound framework
477            x)  add one or more sound cards as devices; add a testmachine
478                sound card first?
479            x)  Dreamcast sound? Generic PCI sound cards?
480    
481    ASC SCSI controller:
482            x)  NetBSD/arc 2.0 uses the ASC controller in a way which GXemul
483                cannot yet handle. (NetBSD 1.6.2 works ok.) (Possibly a problem
484                in NetBSD itself, http://mail-index.netbsd.org/source-changes/
485                2005/11/06/0024.html suggests that.)
486                NetBSD 4.x seems to work? :)
487    
488    Caches / memory hierarchies: (this is mostly MIPS-specific)
489            o)  src/memory*.c: Implement correct cache emulation for
490                all CPU types. (currently only R2000/R3000 is implemented)
491                (per CPU, multiple levels should be possible, associativity etc!)
492            o)  R2000/R3000 isn't _100%_ correct, just almost correct :)
493            o)  Move the -S (fill mem with random) functionality into the
494                memory.c subsystem, not machine.c or wherever it is now
495            o)  ECC stuff, simulation of memory errors?  (Machine dependent)
496            o)  More than 4GB of emulated RAM, when run on a 32-bit host?
497                (using manual swap-out of blocks to disk, ugly)
498            o)  A global command line option should be used to turn
499                cache emulation on or off. When off, caches should be
500                faked like they are right now. When on, caches and
501                memory latencies should be emulated as correctly as
502                possible.
503    
504    File/disk/symbol handling:
505            o)  Make sure that disks can be added/removed during runtime!
506                (Perhaps this needs a reasonably large re-write.)
507            o)  Remove some of the complexity in file format guessing, for
508                    Ultrix kernels that are actually disk images?
509            o)  Better handling of tape files      
510            o)  Read function argument count and types from binaries? (ELF?)
511            o)  Better demangling of C++ names. Note: GNU's C++ differs from e.g.
512                Microsoft's C++, so multiple schemes must be possible. See
513                URL at top of src/symbol_demangle.c for more info.
514    
515    Userland ABI emulation:
516            o)  see src/useremul.c
517    
518    Better framebuffer and X-windows functionality:
519            o)  Generalize the update_x1y1x2y2 stuff to an extend-region()
520                function...
521            o)  -Yx sometimes causes crashes.
522            o)  Simple device access to framebuffer_blockcopyfill() etc,
523                and text output (using the built-in fonts), for dev_fb.
524            o)  CLEAN UP the ugly event code
525            o)  Mouse clicks can be "missed" in the current system; this is
526                not good. They should be put on a stack of some kind.
527            o)  More 2D and 3D framebuffer acceleration.
528            o)  Non-resizable windows?  Or choose scaledown depending
529                    on size (and center the image, with a black border).
530            o)  Different scaledown on different windows?
531            o)  Non-integral scale-up? (E.g. 640x480 -> 1024x768)
532            o)  Switch scaledown during runtime? (Ala CTRL-ALT-plus/minus)
533            o)  Bug reported by Elijah Rutschman on MacOS with weird
534                keys (F5 = cursor down?).
535            o)  Keyboard and mouse events:
536                    x)  Do this for more machines than just DECstation
537                    x)  more X11 cursor keycodes
538                    x)  Keys like CTRL, ALT, SHIFT do not get through
539                        by themselves (these are necessary for example
540                        to change the font of an xterm in X in the
541                        emulator)
542            o)  Generalize the framebuffer stuff by moving _ALL_ X11
543                    specific code to src/x11.c!
544    

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