/[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 38 by dpavlin, Mon Oct 8 16:21:53 2007 UTC
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1  $Id: TODO,v 1.166 2005/08/16 05:44:33 debug Exp $  $Id: TODO,v 1.476 2007/04/14 05:39:47 debug Exp $
2    
3  ===============================================================================  Some things, in totally random order, that I'd like to fix:
4    (Some items in this list are probably out-to-date by now.)
5    
6  High priority stuff:  Dyntrans:
7            x)  Instruction combination collisions? How to avoid easily...
8            x)  Think about how to do both SHmedia and SHcompact in a reasonable
9  MIPS bintrans:              way! (Or AMD64 long/protected/real, for that matter.)
10          x)  call/return address cache?          x)  68K emulation; think about how to do variable instruction
11                lengths across page boundaries.
12  dyntrans:          x)  Dyntrans with valgrind-inspired memory checker. (In memory_rw,
13          x)  memory write protection for ARM, but NOT for Alpha (because              it would be reasonably simple to add; in each individual fast
14                  it has the IMB instruction... hm)              load/store routine = a lot more work, and it would become
15                kludgy very fast.)
16          x)  call/return address cache          x)  Dyntrans with SMP... lots of work to be done here.
17            x)  Dyntrans with cache emulation... lots of work here as well.
18          x)  instr_call sequence analysis support? (Useful for          x)  Remove the concept of base RAM completely; it would be more
19                  handtuning combinations.)              generic to allow RAM devices to be used "anywhere".
20            o)  dev_mp doesn't work well with dyntrans yet
21          x)  opcode statistics support?          o)  In general, IPIs, CAS, LL/SC etc must be made to work with dyntrans
22                  TODO: is instr_call statistics enough?          x)  Redesign/rethink the delay slot mechanism used for e.g. MIPS,
23                    so that it caches a translation (that is, an instruction
24          x)  support for archs that allow transparent unaligned load/stores                  word and the instr_call it was translated to the last
25                    time), so that it doesn't need to do slow
26          x)  SMP: detect when an instruction such as ll/sc or cas is used,                  to_be_translated for each end of page?
27              and "synchronize" approximately the number of executed instructions          x)  Program Counter statistics:
28              (or cycles) across all CPUs.                  Per machine? What about SMP? All data to the same file?
29                    A debugger command should be possible to use to enable/
30          x)  support for variable-length instructions (x86, m68k, ...)                  disable statistics gathering.
31                  Perhaps:  don't increase the next_ic between every                  Configuration file option!
32                  instruction, but let each instruction's handler do          x)  Breakpoints:
33                  that for itself.                  o) Physical vs virtual addresses!
34                  Problem: what about instructions crossing a (virtual)                  o) 32-bit vs 64-bit sign extension for MIPS, and others?
35                          page boundary? They cannot be translated once          x)  INVALIDATION should cause translations in _all_ cpus to be
36                          and for all :( and must be interpreted slowly!              invalidated, e.g. on a write to a write-protected page
37                (containing code)
38          x)  support for THUMB or MIPS16  (arm, mips)          x)  16-bit encodings? (MIPS16, ARM Thumb, 32-bit SH on SH64)
39            x)  Lots of other stuff: see src/cpus/README_DYNTRANS
40          x)  support for Delay slots!  (mips, sparc, hppa)          x)  Native code generation backends:
41                    o)  think carefully about this.
42          x)  Alpha: hahaha, zapnot and inserts/extracts don't                  o)  simple syntax for emitting opcodes; backend implementation
43              compile into very nice code :-|  fix this                      must be optional, so I don't have to write more code
44                        than necessary. after all, the non-native (C) code should
45          x)  64-bit virtual memory translation tables (PPC, etc)                      always work.
46                    o)  convert into native code only after an entire
47          x)  x86: convert to dyntrans. LOTS of stuff to consider.                          block has been translated? probably best.
48                    o)  the "almost native" opcodes may be rearranged,
49                        "peep-hole optimized", etc. and then as a separate step
50  ===============================================================================                      this list of almost native opcodes is written out
51                        as native code.
52  Lower priority, but still important:                  o)  think about delay slots at the end of a block!
53                    o)  x86/amd64 code generator can be very similar... perhaps
54          Redesign the entire "mainbus" concept:                  o)  NOTE that generation is per _ABI_, not per host arch!
55                  o)  Easily configurable interrupt routing in SMP systems.                      the configure script must detect ABI!!!
56                  o)  Specific clock/bus speeds, cpu speeds etc.                  o)  branches to already translated code blocks can
57                  o)  Synchronization over network?                          link the blocks together
58                    o)  load/store are the most important to optimize
59          Caches / memory hierarchies: (this is mostly MIPS-specific)  
60                  o)  MIPS coproc.c: bits in config registers should reflect  Simple Valgrind-like checks?
61                      correct cache sizes for _all_ CPU types. (currently only          o)  Mark every address with bits which tell whether or not the address
62                      implemented for R4000, R1x000, and a few others)              has been written to.
63                  o)  src/memory*.c: Implement correct cache emulation for          o)  What should happen when programs are loaded?  Text/data, bss (zero
64                      all CPU types. (currently only R2000/R3000 is implemented)              filled). But stack space and heap is uninitialized.
65                      (per CPU, multiple levels should be possible,          o)  Uninitialized local variables:
66                      associativity etc!)                  A load from a place on the stack which has not previously
67                  o)  R2000/R3000 isn't _100%_ correct, just almost correct :)                  been stored to => warning. Increasing the stack pointer using
68                  o)  Move the -S (fill mem with random) functionality into the                  any available means should reset the memory to uninitialized.
69                      memory.c subsystem, not machine.c or wherever it is now          o)  If calls to malloc() and free() can be intercepted:
70                  o)  ECC stuff, simulation of memory errors?  (Machine dependant)                  o)  Access to a memory area after free() => warning.
71                  o)  More than 4GB of emulated RAM, when run on a 32-bit host?                  o)  Memory returned by malloc() is marked as not-initialized.
72                      (using manual swap-out of blocks to disk, ugly)                  o)  Non-passive, but good to have: Change the argument
73                  o)  A global command line option should be used to turn                      given to malloc, to return a slightly larger memory
74                      cache emulation on or off. When off, caches should be                      area, i.e.  margin_before + size + margin_after,
75                      faked like they are right now. When on, caches and                      and return the pointer  + margin_before.
76                      memory latencies should be emulated as correctly as                      Any access to the margin_before or _after space results
77                      possible.                      in warnings. (free() must be modified to free the
78                        actually allocated address.)
79          Network layer:  
80                  o)  Multiple networks per emulation, and let different  MIPS:
81                      NICs in machines connect to different networks.          o)  Nicer MIPS status bits in register dumps.
82                  o)  many other issues: see src/net.c          o)  Alignment exceptions.
83            o)  Floating point exception correctness.
84          MIPS CPU emulation:          o)  Fix this? Triggered by NetBSD/sgimips? Hm:
85                  o)  i386 bintrans backend: movn etc, slt[u] for                  to_be_translated(): TODO: unimplemented instruction:
86                          64-bit mode, 64-bit shifts etc                  000000000065102c: 00200800 (d)  rot_00  at,zr,0
87                  o)  Instructions:          o)  Some more work on opcodes.
88                          o)  All ISAs:                  x) MIPS64 revision 2.
89                                  o)  Floating point exception handling, and                          o)  Find out which actual CPUs implement the rev2 ISA!
90                                          add more instructions.                          o)  DROTR32 and similar MIPS64 rev 2 instructions,
91                                  o)  Finish the MIPS16 translator, and test it!                              which have a rotation bit which differs from
92                                  o)  MIPS ISA I, II, III, IV                              previous ISAs.
93                                  o)  MIPS V (SIMD vector stuff?)                          o)  EI and DI instructions for MIPS64/32 rev 2.
94                                  o)  MDMX  (MIPS Digital Media Extension)                              NOTE: These are _NOT_ the same as for R5900!
95                                  o)  MIPS 3D                  x) _MAYBE_ TX79 and R5900 actually differ in their
96                                  o)  MIPS MT (Multi-thread stuff) (What's this?)                     opcodes? Check this carefully!
97                          o)  Warn about mis-used bit fields (ie bits that          o)  Dyntrans: Count register updates are probably not 100% correct yet.
98                              should be all zeroes, warn about if they are not)!          o)  Refactor code for performance and readability/maintainability.
99                              Both for coprocessor registers and for instruction          o)  (Re)implement 128-bit loads/stores for R5900.
100                              opcodes.          o)  R4000 and others:
101                          o)  the special2 stuff is a mess right now                  x)  watchhi/watchlo exceptions, and other exception
102                          o)  warn and/or cause exceptions for unimplemented                      handling details
103                              instructions (depending on CPU type)          o)  R10000 and others:  (R12000, R14000 ?)
104                  o)  R2000/R3000:                  x)  The code before the line
105                          x)  R3000 "tri-byte stores". (What's this?)                          /*  reg[COP0_PAGEMASK] = cpu->cd.mips.coproc[0]->tlbs[0].mask & PAGEMASK_MASK;  */
106                  o)  R4000 and others:                      in cpu_mips.c is not correct for R10000 according to
107                          x)  watchhi/watchlo exceptions, and other exception                      Lemote's Godson patches for GXemul. TODO: Go through all
108                              handling details                      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                  o)  R10000 and others:  (R12000, R14000 ?)                      and make sure everything works with R10000.
110                          x)  memory space, exceptions, ...                      Then test with OpenBSD/sgi?
111                          x)  use cop0 framemask for tlb lookups                  x)  Entry LO mask (as above).
112                              (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)                  x)  memory space, exceptions, ...
113                  o)  Implement load delays?  Warnings on interlocks.                  x)  use cop0 framemask for tlb lookups
114                  o)  Implement all coprocessor 0 bits / functions.                      (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)  coproc 0 selectors! (R4000 ?)  
116                  o)  R4300 (nintendo64, no mmu?), R5900 (playstation2, weird  SuperH:
117                          TLB/cache? 128-bit GPRs, new instructions),          x)  SH4 interrupt controller:
118                          4K (note: NOT R4000), 5K (note: NOT R5000),                  x)  MASKING should be possible!
119                          R6000 (ISA II), R8000          x)  SH4 DMA (0xffa00000)
120                  o)  Multi-cpu stuff:          x)  SH4 UBC (0xff200000)
121                          +)  Interrupt routing (ie devices vs mainbus, or          x)  SH4 timers are going too fast!
122                              connect each device to a fixed cpu)          x)  Store queues can copy 32 bytes at a time, there's no need to
123                          +)  SGI's NUMA architecture. Study              copy individual 32-bit words. (Performance improvement.)
124                                  x)  Linux sources          x)  SH4 BSC (Bus State Controller)
125                                  x)  SGI's specs on NUMA address space          x)  Instruction tracing should include symbols for branch targets,
126                          +)  Ultrix?  NetBSD doesn't do SMP on MIPS yet :-(              and so on, to make the output more human readable.
127                          +)  Own experiments with ycx2.          x)  SH3-specific devices: Pretty much everything!
128            x)  NetBSD/evbsh3, mmeye, hpcsh! Linux?
129          File/disk handling:          x)  Replace pc-relative loads with immediate load, if within the
130                  o)  Better handling of tape files              same page. (Similar to the same optimization for ARM.)
131            x)  Floating point speed!
132          Debugger:          x)  Floating point exception correctness.
133                  o)  Read function argument count and types from binaries? (ELF?)          x)  Think carefully about how to implement SH5/SH64 (for evbsh5).
134                  o)  Demangle C++ names.  
135    Landisk SH4:
136          Userland ABI emulation:          x)  When NetBSD/landisk 4.0 and OpenBSD/landisk 4.1 have been
137                  o)  see src/useremul.c              released, test to see if they work. (If so, update documentation,
138                guestos + index, and set stable=1 in machine_landisk.c.)
139          Terminal based interactive debugger:  
140                  o)  see src/debugger.c  Dreamcast:
141            x)  G2 DMA
142          Terminal/console stuff:          x)  LAN adapter (dev_mb8696x.c).  NetBSD root-on-nfs.
143                  o)  allow emulated serial ports to be connected to the outside          x)  PVR:  Lots of stuff. See dev_pvr.c.
144                      world in a more generic way, or even to other emulated          x)  Better GDROM support
145                      machines(!)          x)  Modem
146            x)  PCI bridge/bus?
147          Regression tests.  (Needs to be totally rewritten, the old framework          x)  Maple bus:
148                  was removed because it was useless.)                  x)  Correct controller input
149                    x)  Mouse input
150          Save state of the whole emulated machine, to be able to load it back          x)  Software emulation of BIOS calls:
151                  in later?  (Memory, all device's states, all registers and                  x)  GD-ROM emulation: Use the GDROM device.
152                  so on.  Like taking a snapshot. (SimOS seems to do this,                  x)  Use the VGA font as a fake ROM font. (Better than
153                  according to its website.))                      nothing.)
154            x)  Make as many as possible of the KOS examples run!
155          Better X-windows functionality:          x)  More homebrew demos/games.
156                  o)  CLEAN UP the ugly event code          x)  SPU: Sound emulation (ARM cpu).
157                  o)  Mouse clicks can be "missed" in the current system; this is          x)  VME processor emulation? "(Sanyo LC8670 "Potato")" according to
158                      not good. They should be put on a stack of some kind.              Wikipedia, LC86K87 according to Comstedt's page. See
159                  o)  More 2D and 3D framebuffer acceleration.              http://www.maushammer.com/vmu.html for a good description of
160                  o)  Non-resizable windows?  Or choose scaledown depending              the differences between LC86104C and the one used in the VME.
161                          on size (and center the image, with a black border).  
162                  o)  Different scaledown on different windows?  Alpha:
163                  o)  Switch scaledown during runtime? (Ala CTRL-ALT-plus/minus)          x)  OSF1 PALcode, Virtual memory support.
164                  o)  Keyboard and mouse events:          x)  PALcode replacement! PAL1E etc opcodes...?
165                          x)  Do this for more machines than just DECstation          x)  Interrupt/exception/trap handling.
166                          x)  more X11 cursor keycodes          x)  Floating point exception correctness.
167                          x)  Keys like CTRL, ALT, SHIFT do not get through          x)  More work on bootup memory and register contents.
168                              by themselves (these are necessary for example          x)  More Alpha machine types, so it could work with
169                              to change the font of an xterm in X in the              OpenBSD, FreeBSD, and Linux too?
170                              emulator)  
171                  o)  Generalize the framebuffer stuff by moving _ALL_ X11  SPARC (both the ISA and the machines):
172                          specific code to src/x11.c!          o)  Implement Adress space identifiers; load/stores etc.
173            o)  Exception/trap/interrupt handling.
174          Statistics:  (this could be interesting)          o)  Save/restore register windows etc! Both v9 and pre-v9!
175                  o)  Save to file and show graphics. It should be possible to          o)  Finish the subcc and addcc flag computation code.
176                      run gxemul after a simulation to just show the graphics,          o)  Add more registers (floating point, control regs etc)
177                      or convert to a .ppm or .tga or similar.          o)  Disassemly of some more instructions?
178                  o)  memory accesses (to measure cache efficiency and          o)  Are sll etc 32-bit sign-extending or zero-extending?
179                          page coloring efficiency)          o)  Floating point exception correctness.
180                  o)  nr of simultaneous ASIDs in use in the TLB, for MIPS          o)  SPARC v8, v7 etc?
181                  o)  percentage of time spent in different "states", such as          o)  More machine modes and devices.
182                      running userland code, kernel code, or idling (for CPUs  
183                      that have such an instruction, or whenever the PC is  Debugger:
184                      inside a specific idle-function (address range)).          o)  How does SMP debugging work? Does it simply use "threads"?
185                      Possible additional state (for example on R3000): caches                  What if the guest OS (running on an emulated SMP machine)
186                      disabled.                  has a usertask running, with userland threads?
187                  o)  position of read/write on (SCSI) disks          o)  Try to make the debugger more modular and, if possible, reentrant!
188            o)  Remove the emul command? (But show network info if showing
189                    machines?)
190            o)  Evaluate expressions within []? That would allow stuff like
191                    cpu[x] where x is an expression.
192            o)  Settings:
193                    x)  Special handlers for Write!
194                            +)  MIPS coproc regs
195                            +)  Alpha/MIPS/SPARC zero registers
196                            +)  x86 64/32/16-bit registers
197                    x)  Value formatter for resulting output.
198            o)  see src/debugger.c for more
199    
200    POWER/PowerPC:
201            x)  Fix DECR timer speed, so it matches the host.
202            x)  NetBSD/prep 3.x triggers a possible bug in the emulator:
203                <wdc_exec_command(0xd005e514,0xd60cdd30,0,8,..)>
204                  <ata_get_xfer(0,0xd60cdd30,0,8,..)>
205                    <0x26c550(&ata_xfer_pool,2,0,8,..)>
206                    <0x35c71c(0x3f27000,0,52,8,..)>
207                  <ata_exec_xfer(0xd005e4c8,0x3f27000,0,13,..)>
208                    <atastart(0xd005e4c8,0x3f27000,0,13,..)>
209                      <__wdccommand_start(0xd005e4c8,0x3f27000,0,13,..)>
210                        <bsw1(&prep_isa_io_space_tag,0x800001f6,0,176,..)>
211                    [ wdc: write to SDH: 0xb0 (sectorsize 2, lba=1, drive 1, head 0) ]
212                        <wdcwait(0xd005e4c8,72,64,0xbb8,..)>
213                          <0x198120(0xd005e4c8,72,64,0xbb8,..)>
214                            <bsr1(&prep_isa_io_space_tag,0,0,0xbb8,..)>
215                            <delay(100,0,0,0xbb8,..)>
216                Note: <bsr1(&prep_isa_io_space_tag,0,0,0xbb8,..)>
217            x)  PPC optimizations; instr combs
218            x)  64-bit stuff: either Linux on G5, or perhaps some hobbyist
219                    version of AIX? (if there exists such a thing)
220            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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