X-Git-Url: https://git.libre-soc.org/?a=blobdiff_plain;f=openpower.mdwn;h=da186f35b69cb6ad4c6d427ea795e555f6f0888e;hb=fc2a6d3269771ffeeb423b4b0d9f6928a318b5c1;hp=0832f97fd2509c80d4b2d9d55c05fdaa915ae079;hpb=1ea9cb27218a7023c2ab83bb94637bc9122332c5;p=libreriscv.git diff --git a/openpower.mdwn b/openpower.mdwn index 0832f97fd..da186f35b 100644 --- a/openpower.mdwn +++ b/openpower.mdwn @@ -1,23 +1,37 @@ # OpenPOWER In the late 1980s [[!wikipedia IBM]] developed a POWER family of processors. -This evolved to a specification known as the Power ISA. In 2019 IBM made the Power ISA [[!wikipedia Open_source]] to be looked after by the existing [[!wikipedia OpenPOWER_Foundation]]. Here is a longer history of [[!wikipedia IBM_POWER_microprocessors]]. +This evolved to a specification known as the POWER ISA. In 2019 IBM made the POWER ISA [[!wikipedia Open_source]], to be looked after by the existing [[!wikipedia OpenPOWER_Foundation]]. Here is a longer history of [[!wikipedia IBM_POWER_microprocessors]]. These IBM proprietary processors +happen to implement what is now known as the POWER ISA. The names +POWER8, POWER9, POWER10 etc. are product designations equivalent to Intel +i5, i7, i9 etc. and are frequently conflated with versions of the POWER ISA (v2.07, v3.0c, v3.1b). -Libre-SOC is basing its [[Simple-V Vectorisation|sv]] CPU extensions on OpenPOWER because it wants to be able to specify a machine that can be completely trusted, and because OpenPOWER is designed for high performance. +Libre-SOC is basing its [[Simple-V Vectorisation|sv]] CPU extensions on POWER ISA, because it wants to be able to specify a machine that can be completely trusted, and because POWER, thanks to IBM's involvement, +is designed for high performance. + +See wikipedia page + + +very useful resource describing all assembly instructions + # Evaluation EULA released! looks good. + -Links +# Links * OpenPOWER Membership - + * OpenPower HDL Mailing list * [[openpower/isatables]] +* [[openpower/whitepapers]] * [[openpower/isa]] - pseudo-code extracted from POWER V3.0B PDF spec * [[openpower/gem5]] * [[openpower/sv]] +* [[openpower/prefix_codes]] Decode/encode prefix-codes, used by JPEG, DEFLATE, etc. +* [[openpower/opcode_regs_deduped]] * [[openpower/simd_vsx]] * [[openpower/ISA_WG]] - OpenPOWER ISA Working Group * [[openpower/pearpc]] @@ -52,6 +66,7 @@ Summary * Opcode 4 Signal Processing (SPE) * Opcode 4 Vectors or Opcode 60 VSX (600+ additional instructions) * Avoidable legacy opcodes +* SIMD. it's awful. # SimpleV @@ -66,14 +81,6 @@ Thus it is completely unnecessary to add any vector opcodes - at all - saving hugely on both hardware and compiler development time when the concept is dropped on top of a pre-existing ISA. -## Condition Registers - -Branch Facility (Section 2.3.1 V2.07B and V3.0B) has 4-bit registers: CR0 and CR1. When SimpleV is active, it may be better to set CR6 (the Vector CR field) instead. - -## Carry - -SimpleV extends (wraps) *scalar* opcodes with a hardware-level for-loop. Therefore, each scalar operation with a carry-in and carry-out will **require its own carry in and out bit**. Most sensible location to use is the CRs - # Integer Overflow / Saturate Typically used on vector operations (audio DSP), it makes no sense to have separate opcodes (Opcode 4 SPE). To be done instead as CSRs / vector-flags on *standard* arithmetic operations.