K6-2+ and 6x86MX missing instructions

[Torinde]

K6-2+, K6-III+ and 6x86MX are listed cpu.h, but I don't see the extra instructions added by those CPUs in the code

K6-2+ : PF2IW, PFNACC, PFPNACC, PI2FW, PSWAPD (relevant also for the future Athlon emulation)
6x86MX : PAVEB, PADDSIW, PMAGW, PDISTIB, PSUBSIW, PMVZB, PMVNZB, PMVLZB, PMVGEZB, PMULHRIW, PMACHRIW; FTSTP, FRINT2, FRICHOP, FRINEAR

Of course, I couldn't find also the 3DNow! Pro from Geode GX/LX) : PFRSQRTV, PFRCPV - but those CPUs aren't listed, so that's as expected.

Related to joncampbell123/dosbox-x#3217, sarah-walker-pcem/pcem#85

[fuel-pcbox]

Do you know of any software that actually uses said instructions? I might end up removing 6x86MX support from the code, but K6-2+ is rather important. I could go ahead and implement the K6-2+ instructions, but I have no idea how to test them.

[Torinde]

List of games and software in 3DNow! mode
Some versions of Bochs utilize 3DNow (and some emulate it)

Not sure which software uses 3DNow!+ vs regular 3DNow!...

Cyrix EMMI - info 1,3,4 and maybe software: 6x86ctl1.zip, 6xopt080.zip
From here - in the same folder are other Cyrix CPU tools, maybe some of all those at least checks for MII/M2/MX ?

• x86c2.zip B 18627 960923 Enables advanced features of Cyrix Cx5x86 CPU
• 686fast4.zip B 18769 981114 686FAST: Speedup for Cyrix/IBM/TI CPU
• 6x86ctl1.zip B 13765 970103 Change/view the Cyrix 6x86 CPU options
• 6xopt080.zip B 143858 981222 6x86opt v0.80: Optimizes the 6x86 (M1/M2) CPU
• cyrix100.zip B 122481 940406 Cyrix 486DLC/486DR/486SLC CPU config. utility

For example, the 6x86opt has:
6X86OPT.EXE 45296 bytes 6x86opt, the optimizer
6X86OPT.TXT 32317 bytes This textfile
6X86SET.EXE 102656 bytes 6x86set, the setup utility for M1
6x86SET2.EXE 107136 bytes 6x86set for the 6x86MX == M2
6X86SET.TXT 5819 bytes Info on 6x86set
CPUIDEN.EXE 10528 bytes CPUID instruction enabler/disabler/toggler

One of those has a switch
" -MMXPLUS(-M) ; Set the MMXPLUS bit (CCR7:0). M2 only. This bit
enables the Cyrix Extended MMX instructions."

Ideally, I would assume there must be at least some Cyrix demo/benchmark utilized when promoting the product...

There is also a CPU flag in Linux for those: cxmmx Cyrix MMX extensions

[Torinde]

Cyrix EMMI is supported also by later MediaGXm and Geode GX1 well into the 2000s, so maybe some embedded or other application used those.

[Torinde]

K6-2+ instructions apparently were added by fc53fce

Remains:

• 6x86MX: Cyrix core EMMI

..and if support is added for appropriate platforms:

• Geode GXm/GXLV/GX1 / MediaGXm: Cyrix core EMMI
• Geode GX2/GX/LX: Cyrix core 3DNow! Pro PFRSQRTV, PFRCPV
  • emulated by FEX-Emu
  • used in OLPC
• Geode NX: Athlon XP core