Linux Kernel Module Cheat

24.22.7.2. gem5 DerivO3CPU default functional units

On gem5 3ca404da175a66e0b958165ad75eb5f54cb5e772, after running:

./run   \
  --arch aarch64 \
  --emulator gem5 \
  --userland userland/arch/aarch64/freestanding/linux/hello.S \
  --trace-insts-stdout \
  -- \
  --cpu-type Derivo3CPU \
  --caches

we see:

[system.cpu]
type=DerivO3CPU
children=branchPred dcache dtb fuPool icache interrupts isa itb power_state tracer workload

and following fuPool:

[system.cpu.fuPool]
type=FUPool
children=FUList0 FUList1 FUList2 FUList3 FUList4 FUList5 FUList6 FUList7 FUList8 FUList9

so for example FUList0 is:

[system.cpu.fuPool.FUList0]
type=FUDesc
children=opList
count=6
eventq_index=0
opList=system.cpu.fuPool.FUList0.opList

[system.cpu.fuPool.FUList0.opList]
type=OpDesc
eventq_index=0
opClass=IntAlu
opLat=1
pipelined=true

and FUList1:

[system.cpu.fuPool.FUList1.opList0]
type=OpDesc
eventq_index=0
opClass=IntMult
opLat=3
pipelined=true

[system.cpu.fuPool.FUList1.opList1]
type=OpDesc
eventq_index=0
opClass=IntDiv
opLat=20
pipelined=false

So summarizing all units we have:

0, 1: IntAlu with opLat=3
2: IntMult with opLat=3 and IntDiv with opLat=20
3: FloatAdd, FloatCmp, FloatCvt with opLat=2
TODO lazy to finish the list :-)