General
-------
-- [ls][dw][lr] report broken (aligned) BadVAddr
-- Missing per-CPU instruction decoding, currently all implemented
- instructions are regarded as valid
-- pcnet32 does not work for little endian emulation on big endian host
- (probably not mips specific, but observable for mips-malta)
-- CP1 enable/disable is checked at translation time, not at execution
- time, so it will have delayed effect.
+- Unimplemented ASEs:
+ - MIPS16
+ - MDMX
+ - SmartMIPS
+ - DSP r1
+ - DSP r2
+- MT ASE only partially implemented and not functional
+- Shadow register support only partially implemented,
+ lacks set switching on interrupt/exception.
+- 34K ITC not implemented.
+- A general lack of documentation, especially for technical internals.
+ Existing documentation is x86-centric.
+- Reverse endianness bit not implemented
+- The TLB emulation is very inefficient:
+ Qemu's softmmu implements a x86-style MMU, with separate entries
+ for read/write/execute, a TLB index which is just a modulo of the
+ virtual address, and a set of TLBs for each user/kernel/supervisor
+ MMU mode.
+ MIPS has a single entry for read/write/execute and only one MMU mode.
+ But it is fully associative with randomized entry indices, and uses
+ up to 256 ASID tags as additional matching criterion (which roughly
+ equates to 256 MMU modes). It also has a global flag which causes
+ entries to match regardless of ASID.
+ To cope with these differences, Qemu currently flushes the TLB at
+ each ASID change. Using the MMU modes to implement ASIDs hinges on
+ implementing the global bit efficiently.
+- save/restore of the CPU state is not implemented (see machine.c).
MIPS64
------
-- No 64bit TLB support
-- no 64bit wide registers for FPU
-- 64bit mul/div handling broken
+- Userland emulation (both n32 and n64) not functional.
"Generic" 4Kc system emulation
------------------------------
-- Doesn't correspond to any real hardware.
+- Doesn't correspond to any real hardware. Should be removed some day,
+ U-Boot is the last remaining user.
+
+PICA 61 system emulation
+------------------------
+- No framebuffer support yet.
MALTA system emulation
----------------------
- We fake firmware support instead of doing the real thing
-- Real firmware falls over when trying to init RAM, presumably due
- to lacking I2C emulation.
+- Real firmware (YAMON) falls over when trying to init RAM, presumably
+ due to lacking system controller emulation.
+- Bonito system controller not implemented
+- MSC1 system controller not implemented
projects / qemu / blobdiff