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ths2c52c812007-01-17 20:03:15 +00001Unsolved issues/bugs in the mips/mipsel backend
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ths15dcf5a2007-01-19 17:56:23 +00004General
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thsd0f48072007-10-13 19:00:52 +00006- Unimplemented ASEs:
thsd0f48072007-10-13 19:00:52 +00007 - MDMX
8 - SmartMIPS
9 - DSP r1
10 - DSP r2
11- MT ASE only partially implemented and not functional
12- Shadow register support only partially implemented,
13 lacks set switching on interrupt/exception.
14- 34K ITC not implemented.
15- A general lack of documentation, especially for technical internals.
16 Existing documentation is x86-centric.
17- Reverse endianness bit not implemented
18- The TLB emulation is very inefficient:
19 Qemu's softmmu implements a x86-style MMU, with separate entries
20 for read/write/execute, a TLB index which is just a modulo of the
21 virtual address, and a set of TLBs for each user/kernel/supervisor
22 MMU mode.
23 MIPS has a single entry for read/write/execute and only one MMU mode.
24 But it is fully associative with randomized entry indices, and uses
25 up to 256 ASID tags as additional matching criterion (which roughly
26 equates to 256 MMU modes). It also has a global flag which causes
27 entries to match regardless of ASID.
28 To cope with these differences, Qemu currently flushes the TLB at
29 each ASID change. Using the MMU modes to implement ASIDs hinges on
30 implementing the global bit efficiently.
thsbec19c02008-05-07 15:39:12 +000031- save/restore of the CPU state is not implemented (see machine.c).
ths2c52c812007-01-17 20:03:15 +000032
ths15dcf5a2007-01-19 17:56:23 +000033MIPS64
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ths540635b2007-09-30 01:58:33 +000035- Userland emulation (both n32 and n64) not functional.
ths15dcf5a2007-01-19 17:56:23 +000036
37"Generic" 4Kc system emulation
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thsebbd0ff2008-06-24 22:04:41 +000039- Doesn't correspond to any real hardware. Should be removed some day,
40 U-Boot is the last remaining user.
ths15dcf5a2007-01-19 17:56:23 +000041
ths509b8ab2007-04-28 21:44:04 +000042PICA 61 system emulation
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44- No framebuffer support yet.
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ths15dcf5a2007-01-19 17:56:23 +000046MALTA system emulation
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ths2c52c812007-01-17 20:03:15 +000048- We fake firmware support instead of doing the real thing
thsebbd0ff2008-06-24 22:04:41 +000049- Real firmware (YAMON) falls over when trying to init RAM, presumably
50 due to lacking system controller emulation.
ths0300e3f2007-12-17 03:53:42 +000051- Bonito system controller not implemented
52- MSC1 system controller not implemented