nlnet_2019_coriolis2.mdwn

   1 # NLnet.net LIP6.fr Coriolis2 proposal
   2
   3 * [[questions]]
   4 * approved 20dec2019
   5 * MOU TBD
   6 * 2019-10-029
   7 * NLNet Project Page <https://nlnet.nl/project/Coriolis2/>
   8
   9 ## Project name
  10
  11 The Libre-RISCV SoC, Coriolis2 ASIC Layout Collaboration
  12
  13 ## Website / wiki
  14
  15 <https://libre-riscv.org/nlnet_2019_coriolis2>
  16
  17 Please be short and to the point in your answers; focus primarily on
  18 the what and how, not so much on the why. Add longer descriptions as
  19 attachments (see below). If English isn't your first language, don't
  20 worry - our reviewers don't care about spelling errors, only about
  21 great ideas. We apologise for the inconvenience of having to submit in
  22 English. On the up side, you can be as technical as you need to be (but
  23 you don't have to). Do stay concrete. Use plain text in your reply only,
  24 if you need any HTML to make your point please include this as attachment.
  25
  26 ## Abstract: Can you explain the whole project and its expected outcome(s).
  27
  28 The Libre RISC-V SoC is being developed to provide a privacy-respecting
  29 modern processor, developed transparently and as libre to the bedrock
  30 as possible.  This means not just the software running on the processor:
  31 it means the actual hardware design and the hardware layout, right down
  32 to the transistor level.
  33
  34 It is necessary, therefore, to use libre-licensed VLSI Layout tools
  35 rather than pay for proprietary software that, apart from being incredibly
  36 expensive, could potentially compromise the integrity of the project.
  37
  38 We therefore intend to collaborate with engineers from LIP6, to use
  39 and improve their VLSI Layout tool, Coriolis2, in conjunction with
  40 Chips4Makers, to create the layout that Chips4Makers will then put into
  41 a 180nm 300mhz test chip.
  42
  43 # Have you been involved with projects or organisations relevant to this project before? And if so, can you tell us a bit about your contributions?
  44
  45 Luke Leighton is an ethical technology specialist who has a consistent
  46 24-year track record of developing code in a real-time transparent
  47 (fully libre) fashion, and in managing Software Libre teams.  He is the
  48 lead developer on the Libre RISC-V SoC.
  49
  50 Jean-Paul Chaput is the lead engineer on the Alliance and Coriolis2
  51 tools for VLSI backend layout, from LIP6.
  52
  53 # Requested Amount
  54
  55 EUR 50,000.
  56
  57 # Explain what the requested budget will be used for?
  58
  59 The key initial milestone for the 2018 NLNet Libre RISC-V SoC Project
  60 is the FPGA target: a working design that can run in an FPGA at approximately
  61 50Mhz.  The next logical step is to do the layout.
  62
  63 However, FPGA targets have some quirks which help accelerate FPGAs (not ASICs):
  64 an on-board DSP, specialist memory, and so on.  Without these "crutches"
  65 the design must be augmented and adapted to suit ASIC layout.
  66
  67 As we are using nmigen for the HDL front-end and yosys for the HDL
  68 back-end, we will need to work with the nmigen developers in order to
  69 augment nmigen to cope with the task of creating "netlists" suitable for
  70 ASICs.  Whilst yosys (the actual "netlist" generator) has been utilised
  71 for this task repeatedly and successfully, and whilst the prior version,
  72 "migen", was also used, nmigen has not yet been ASIC proven.
  73
  74 Once a "netlist" is available, the Coriolis2 VLSI tool will be used to
  75 actually create the layers of the chip.  Given the size and capabilities
  76 of the chip, we anticipate issues here, which we will need the support
  77 of LIP6's engineers to solve.
  78
  79 The layout itself is also dependent on what is called "Cell Libraries".
  80 One is "NSXLIB" which contains OR and AND gates to create MUXes and XORs.
  81 Another is an "SRAM" Library (memory), and another is a "GPIO" Cell
  82 Library.  Chips4Makers will be working on these low-level blocks for
  83 us (under a separate Programme), however we again anticipate issues -
  84 related to Foundry NDAs - which will hamper the communications process.
  85
  86 So therefore, the requested budget will be used for:
  87
  88 * Augmentation and adaptation of the Libre RISC-V SoC HDL to ASIC layout
  89 * Engineers to work on the layout using Alliance / Coriolos2 VLSI, from lip6
  90 * Engineers to bug-fix or augment Alliance / Coriolis2
  91 * Essential augmentations to nmigen to make it ASIC-layout-capable
  92
  93 All of these will be and are entirely libre-licensed software: there will
  94 be no proprietary software tools utilised in this process.
  95
  96
  97 # Does the project have other funding sources, both past and present?
  98
  99 The overall project has sponsorship from Purism as well as a prior grant
 100 from NLNet.  However that is for specifically covering the development
 101 of the RTL (the hardware source code).
 102
 103 There is no source of funds for the work on the *next* stage: the actual
 104 VLSI ASIC Layout.  Chips4Makers is however putting in an *additional*
 105 (and separate) funding application for the stage after *this*: the
 106 creation of the Cell Libraries that will be used in the VLSI ASIC Layout.
 107
 108 All these three projects are separate and distinct (despite being related
 109 to the same CPU), and funding may not cross over from one project to
 110 the other.
 111
 112 # Compare your own project with existing or historical efforts.
 113
 114 There are several Open VLSI Tool suites:
 115
 116 * GNU Electric: https://www.gnu.org/software/electric/
 117 * MAGIC: http://opencircuitdesign.com/magic/
 118 * The OpenROAD Project: https://theopenroadproject.org/ (using MAGIC)
 119 * QFlow: http://opencircuitdesign.com/qflow/
 120 * Toped: http://www.toped.org.uk/
 121
 122 and a few more.  We choose Coriolis2 because of its python interface.
 123 The VLSI Layout is actually done as a *python* program.  With nmigen
 124 (the HDL) being in python, we anticipate the same OO benefits to be
 125 achievable in coriolis2 as well.
 126
 127 The case for the Libre RISC-V SoC itself was made already in the initial
 128 2018.02 proposal.  That has not changed: there are no Libre / Open Projects
 129 approaching anything like the complexity and product market opportunities
 130 of the Libre RISC-V SoC, which is being designed to be a quad-core 800mhz
 131 multi-issue out-of-order design.  All other Libre / Open processors such
 132 as Raven, and many more, have a goal set in advance not to exceed around
 133 the 350mhz mark, and are single-core.
 134
 135 Other projects which are "open", such as the Ariane Processor, are
 136 developed by universities, and in the case of Ariane were *SPECIFICALLY*
 137 designed by and for the use of proprietary toolchains, such as those from
 138 Cadence, Synopsys and Mentor Graphics.  Despite the source code being
 139 "open", there was absolutely no expectation that the processor of the
 140 same capability as the Libre RISC-V SoC would use Libre / Open tools.
 141
 142 Although our first ASIC (thanks to Chips4Makers) will be only 180nm,
 143 single-core and a maximum of around 350mhz, this is just the first
 144 stepping stone to a much larger processor.
 145
 146 ## What are significant technical challenges you expect to solve during the project, if any?
 147
 148 Some of these have been mentioned above:
 149
 150 * NDAs by Foundries may interfere with the ability for Chips4Makers to
 151   communicate with LIP6 regarding the necessary changes to NSXLIB which
 152   meet the TSMC Foundry "Design Rule Checks" (DRCs).
 153 * Bugs or missing features in nmigen, yosys, coriolis2, NSXLIB, OpenRAM,
 154   and the knock-on implications throughout the chain, right the way up
 155   to the *actual* Libre RISC-V SoC's HDL source code itself, all need to
 156   be dealt with.
 157 * Circuit simulation and unit testing is going to be a major factor, and
 158   a huge utilisation of Computing power.  Machines with "only" 16 GB of RAM
 159   and high-end quad-core processors are going to be hopelessly inadequate.
 160
 161 ## Describe the ecosystem of the project, and how you will engage with relevant actors and promote the outcomes?
 162
 163 LIP6 have their own mailing list for the (transparent) discussion of
 164 issues related to coriolis2: <alliance-users@asim.lip6.fr>.  The Libre RISC-V
 165 SoC has a full set of resources for Libre Project Management and development:
 166 mailing list, bugtracker, git repository and wiki - all listed here:
 167 <https://libre-riscv.org/>
 168
 169 In addition, we have a Crowdsupply page
 170 <https://www.crowdsupply.com/libre-risc-v/m-class> which provides a public
 171 gateway, and heise.de, reddit, phoronix, slashdot and other locations have
 172 all picked up the story.  The list is updated and maintained here:
 173 <https://libre-riscv.org/3d_gpu/>
 174
 175 # Extra info to be submitted
 176
 177 * <http://libre-riscv.org/3d_gpu/>
 178 * <https://www-soc.lip6.fr/equipe-cian/logiciels/coriolis/>
 179 * <https://nlnet.nl/project/Libre-RISCV/>
 180 * <https://chips4makers.io/blog/>
 181