updates/023_2020mar26_decoder_emulator_started.mdwn

   1 So many things happened since the last update they actually need to go
   2 in the main update, even in summary form.  One big thing: Raptor Engineering
   3 sponsored us with remote access to a TALOS II Workstation!
   4
   5 # Introduction
   6
   7 Here's the summary (if it can be called a summary):
   8
   9 * [An announcement](http://lists.libre-riscv.org/pipermail/libre-riscv-dev/2020-March/004995.html)
  10   that we got the funding (which is open to anyone - hint, hint) resulted in
  11   at least three people reaching out to join the team.  "We don't need
  12   permission to own our own hardware" got a *really* positive reaction.
  13 * New team member, Jock (hello Jock!) starts on the coriolis2 layout,
  14   after Jean-Paul from LIP6.fr helped to dramatically improve how coriolis2
  15   can be used.  This resulted in a
  16   [tutorial](https://libre-riscv.org/HDL_workflow/coriolis2/) and a
  17   [huge bug report discussion](http://bugs.libre-riscv.org/show_bug.cgi?id=178)
  18 * Work has started on the
  19   [POWER ISA decoder](http://bugs.libre-riscv.org/show_bug.cgi?id=186),
  20   verified through
  21   [calling GNU AS](https://git.libre-riscv.org/?p=soc.git;a=blob;f=src/soc/decoder/test/test_decoder_gas.py;h=9238d3878d964907c5569a3468d6895effb7dc02;hb=56d145e42ac75626423915af22d1493f1e7bb143) (yes, really!)
  22   and on a mini-simulator
  23   [calling QEMU](https://git.libre-riscv.org/?p=soc.git;a=blob;f=src/soc/simulator/qemu.py;h=9eb103bae227e00a2a1d2ec4f43d7e39e4f44960;hb=56d145e42ac75626423915af22d1493f1e7bb143)
  24   for verification.
  25 * Jacob's simple-soft-float library growing
  26   [Power FP compatibility](http://bugs.libre-riscv.org/show_bug.cgi?id=258)
  27   and python bindings.
  28 * A Conference call with OpenPOWER Foundation Director, Hugh, and Timothy
  29   Pearson from RaptorCS has been established every two weeks.
  30 * The OpenPOWER Foundation is also running some open
  31   ["Virtual Coffee"](https://openpowerfoundation.org/openpower-virtual-coffee-calls/)
  32   weekly round-table calls for anyone interested, generally, in OpenPOWER
  33   development.
  34 * Tim sponsors our team with access to a Monster Talos II system with a
  35   whopping 128 GB RAM.  htop lists a staggering 72 cores (18 real
  36   with 4-way hyperthreading).
  37 * [Epic MegaGrants](http://lists.libre-riscv.org/pipermail/libre-riscv-dev/2020-March/005262.html)
  38   reached out (hello!) to say they're still considering our
  39   request.
  40 * A marathon 3-hour session with [NLNet](http://nlnet.nl) resulted
  41   in the completion of the
  42   [Milestone tasks list(s)](http://bugs.libre-riscv.org/buglist.cgi?component=Milestones&list_id=567&resolution=---)
  43   and a
  44   [boat-load](http://lists.libre-riscv.org/pipermail/libre-riscv-dev/2020-March/thread.html)
  45   of bug reports to the list.
  46 * Immanuel Yehowshua is participating in the Georgia Tech
  47   [https://create-x.gatech.edu/](Create-X) Programme, and is establishing
  48   a Public Benefit Corporation in Atlanta, as an ethical vehicle for VC
  49   Funding.
  50 * A [Load/Store Buffer](http://bugs.libre-riscv.org/show_bug.cgi?id=216)
  51   design and
  52   [further discussion](http://bugs.libre-riscv.org/show_bug.cgi?id=257)
  53   including on
  54   [comp.arch](https://groups.google.com/forum/#!topic/comp.arch/cbGAlcCjiZE)
  55   inspired additional writeup
  56   on the
  57   [6600 scoreboard](https://libre-riscv.org/3d_gpu/architecture/6600scoreboard/)
  58   page.
  59
  60 Well dang, as you can see, suddenly it just went ballistic.  There's
  61 almost certainly things left off the list.  For such a small team there's
  62 a heck of a lot going on.  We have an awful lot to do, in a short amount
  63 of time: the 180nm tape-out is in October 2020 - only 7 months away.
  64
  65 # NLNet Funding announcement
  66
  67 TODO
  68
  69 # Coriolis2 experimentation started
  70
  71 TODO
  72
  73 # POWER ISA decoder and Simulator
  74
  75 TODO
  76
  77 # simple-soft-float Library and POWER FP emulation
  78
  79 The [simple-soft-float](https://salsa.debian.org/Kazan-team/simple-soft-float) library is a floating-point library Jacob wrote with the intention of being a reference implementation of IEEE 754 for hardware testing purposes. It's specifically designed to be written to be easier to understand instead of having the code obscured in pursuit of speed:
  80
  81  * Being easier to understand helps prevent bugs where the code does not match the IEEE spec.
  82  * It uses the [algebraics](https://salsa.debian.org/Kazan-team/algebraics) library that Jacob wrote since that allows using numbers that behave like exact real numbers, making reasoning about the code simpler.
  83  * It is written in Rust rather than highly-macro-ified C, since that helps with readability since operations aren't obscured, as well as safety, since Rust proves at compile time that the code won't seg-fault unless you specifically opt-out of those guarantees by using `unsafe`.
  84
  85 It currently supports 16, 32, 64, 128-bit FP for RISC-V, along with having a `DynamicFloat` type which allows dynamically specifying all aspects of how a particular floating-point type behaves -- if one wanted, they could configure it as a 2048-bit floating-point type.
  86
  87 It also has Python bindings, thanks to the awesome [PyO3](https://pyo3.rs/) library for writing Python bindings in Rust.
  88
  89 We decided to write simple-soft-float instead of extending the industry-standard [Berkeley softfloat](http://www.jhauser.us/arithmetic/SoftFloat.html) library because of a range of issues, including not supporting Power FP, requiring recompilation to switch which ISA is being emulated, not supporting all the required operations, architectural issues such as depending on global variables, etc. We are still testing simple-soft-float against Berkeley softfloat where we can, however, since Berkeley softfloat is widely used and highly likely to be correct.
  90
  91 simple-soft-float is [gaining support for Power FP](http://bugs.libre-riscv.org/show_bug.cgi?id=258), which requires rewriting a lot of the status-flag handling code since Power supports a much larger set of floating-point status flags and exceptions than most other ISAs.
  92
  93 Thanks to RaptorCS for giving us remote access to a Power9 system, since that makes it much easier verifying that the test cases are correct.
  94
  95 API Docs for stable releases of both [simple-soft-float](https://docs.rs/simple-soft-float) and [algebraics](https://docs.rs/algebraics) are available on docs.rs.
  96
  97 # OpenPOWER Conference calls
  98
  99 TODO
 100
 101 # OpenPower Virtual Coffee Meetings
 102
 103 TODO
 104
 105 # Sponsorship by RaptorCS with a TALOS II Workstation
 106
 107 TODO
 108
 109 # Epic Megagrants
 110
 111 TODO
 112
 113 # NLNet Milestone tasks
 114
 115 TODO
 116
 117 # Georgia Tech CREATE-X
 118
 119 TODO
 120
 121 # LOAD/STORE Buffer and 6600 design documentation
 122
 123 TODO
 124
 125 # Conclusion
 126
 127 TODO
 128