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   [Create-X](https://create-x.gatech.edu/) 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 * [Public-Inbox](http://bugs.libre-riscv.org/show_bug.cgi?id=181) was
  60   installed successfully on the server, which is in the process of
  61   moving to a [new domain name](http://bugs.libre-riscv.org/show_bug.cgi?id=182)
  62   [Libre-SOC](http://libre-soc.org)
  63 * Build Servers have been set up with
  64   [automated testing](http://lists.libre-riscv.org/pipermail/libre-riscv-dev/2020-March/005364.html)
  65   being established
  66
  67 Well dang, as you can see, suddenly it just went ballistic.  There's
  68 almost certainly things left off the list.  For such a small team there's
  69 a heck of a lot going on.  We have an awful lot to do, in a short amount
  70 of time: the 180nm tape-out is in October 2020 - only 7 months away.
  71
  72 With this update we're doing something slightly different: a request
  73 has gone out [to the other team members](http://lists.libre-riscv.org/pipermail/libre-riscv-dev/2020-March/005428.html)
  74 to say a little bit about what each of them is doing.  This also helps me
  75 because these updates do take quite a bit of time to write.
  76
  77 # NLNet Funding announcement
  78
  79 An announcement went out
  80 [last year](https://lists.gnu.org/archive/html/libreplanet-discuss/2019-09/msg00170.html)
  81 that we'd applied for funding, and we got some great responses and
  82 feedback (such as "don't use patented AXI4").  The second time, we
  83 sent out a "we got it!" message and got some really nice private and
  84 public replies, as well as requests from people to join the team.
  85 More on that when it happens.
  86
  87 # Coriolis2 experimentation started
  88
  89 TODO by Jock http://bugs.libre-riscv.org/show_bug.cgi?id=217#c44
  90
  91 # POWER ISA decoder and Simulator
  92
  93 TODO
  94
  95 # simple-soft-float Library and POWER FP emulation
  96
  97 The
  98 [simple-soft-float](https://salsa.debian.org/Kazan-team/simple-soft-float)
  99 library is a floating-point library Jacob wrote with the intention
 100 of being a reference implementation of IEEE 754 for hardware testing
 101 purposes. It's specifically designed to be written to be easier to
 102 understand instead of having the code obscured in pursuit of speed:
 103
 104 * Being easier to understand helps prevent bugs where the code does not
 105   match the IEEE spec.
 106 * It uses the [algebraics](https://salsa.debian.org/Kazan-team/algebraics)
 107   library that Jacob wrote since that allows using numbers that behave
 108   like exact real numbers, making reasoning about the code simpler.
 109 * It is written in Rust rather than highly-macro-ified C, since that helps with
 110   readability since operations aren't obscured, as well as safety, since Rust
 111   proves at compile time that the code won't seg-fault unless you specifically
 112   opt-out of those guarantees by using `unsafe`.
 113
 114 It currently supports 16, 32, 64, 128-bit FP for RISC-V, along with
 115 having a `DynamicFloat` type which allows dynamically specifying all
 116 aspects of how a particular floating-point type behaves -- if one wanted,
 117 they could configure it as a 2048-bit floating-point type.
 118
 119 It also has Python bindings, thanks to the awesome
 120 [PyO3](https://pyo3.rs/) library for writing Python bindings in Rust.
 121
 122 We decided to write simple-soft-float instead
 123 of extending the industry-standard [Berkeley
 124 softfloat](http://www.jhauser.us/arithmetic/SoftFloat.html) library
 125 because of a range of issues, including not supporting Power FP, requiring
 126 recompilation to switch which ISA is being emulated, not supporting
 127 all the required operations, architectural issues such as depending on
 128 global variables, etc. We are still testing simple-soft-float against
 129 Berkeley softfloat where we can, however, since Berkeley softfloat is
 130 widely used and highly likely to be correct.
 131
 132 simple-soft-float is [gaining support for Power
 133 FP](http://bugs.libre-riscv.org/show_bug.cgi?id=258), which requires
 134 rewriting a lot of the status-flag handling code since Power supports a
 135 much larger set of floating-point status flags and exceptions than most
 136 other ISAs.
 137
 138 Thanks to RaptorCS for giving us remote access to a Power9 system,
 139 since that makes it much easier verifying that the test cases are correct.
 140
 141 API Docs for stable releases of both
 142 [simple-soft-float](https://docs.rs/simple-soft-float) and
 143 [algebraics](https://docs.rs/algebraics) are available on docs.rs.
 144
 145 One of the really important things about these libraries: they're not
 146 specifically coded exclusively for Libre-SOC: like softfloat-3 itself
 147 (and also like the [IEEE754 FPU](https://git.libre-riscv.org/?p=ieee754fpu.git))
 148 they're intended for *general-purpose* use by other projects.  These are
 149 exactly the kinds of side-benefits for the wider Libre community that
 150 sponsorship, from individuals, Foundations (such as NLNet) and Companies
 151 (such as Purism and Raptor Engineering) brings.
 152
 153 # OpenPOWER Conference calls
 154
 155 TODO
 156
 157 # OpenPower Virtual Coffee Meetings
 158
 159 The "Virtual Coffee Meetings", announced
 160 [here](https://openpowerfoundation.org/openpower-virtual-coffee-calls/)
 161 are literally open to anyone interested in OpenPOWER (if you're strictly
 162 Libre there's a dial-in method).  These calls are not recorded, it's
 163 just an informal conversation.
 164
 165 What's a really nice surprise is finding
 166 out that Paul Mackerras, whom I used to work with 20 years ago, is *also*
 167 working on OpenPOWER, specifically
 168 [microwatt](https://github.com/antonblanchard/microwatt), being managed
 169 by Anton Blanchard.
 170
 171 A brief discussion led to learning that Paul is looking at adding TLB
 172 (Virtual Memory) support to microwatt, specifically the RADIX TLB.
 173 I therefore pointed him at the same resource
 174 [(power-gem5)](https://github.com/power-gem5/gem5/tree/gem5-experimental)
 175 that Hugh had kindly pointed me at, the week before, and did a
 176 [late night write-up](http://lists.libre-riscv.org/pipermail/libre-riscv-dev/2020-March/005445.html)
 177
 178 My feeling is that these weekly round-table meetings are going to be
 179 really important for everyone involved in OpenPOWER.  It's a community:
 180 we help each other.
 181
 182 # Sponsorship by RaptorCS with a TALOS II Workstation
 183
 184 TODO http://lists.libre-riscv.org/pipermail/libre-riscv-dev/2020-March/005291.html
 185
 186 # Epic Megagrants
 187
 188 TODO
 189
 190 # NLNet Milestone tasks
 191
 192 TODO
 193
 194 # Georgia Tech CREATE-X
 195
 196 TODO
 197
 198 # LOAD/STORE Buffer and 6600 design documentation
 199
 200 TODO
 201
 202 # Public-Inbox and Domain Migration
 203
 204 TODO
 205
 206 # Build Servers
 207
 208 TODO
 209
 210 # Conclusion
 211
 212 TODO
 213
 214