Menu
Home
People
Places
Arts
History
Plants & Animals
Science
Life & Culture
Technology
Reference.org
OpenPOWER Microwatt
open-in-new
<h2 id="design">Design</h2> <p>Microwatt is a tiny <a href="/facts/64-bit/AgvkQHkM">64-bit</a> <a href="/facts/Endianness/wbrQnyu3">bi-endian</a> <a href="/facts/Scalar_processor/Rwma07cc">scalar</a> <a href="/facts/Arithmetic_logic_unit/SgIjPzSc">integer</a> processor core, implementing a subset of the Power ISA 3.0 instruction set. It has 32× 64-bit <a href="/facts/Processor_register/32RvbUdz">general purpose registers</a> and 32x 64-bit <a href="/facts/Processor_register/32RvbUdz">floating-point registers</a>. It uses <a href="/facts/Wishbone_(computer_bus)/xTu4vkDw">Wishbone</a> for the memory interface.<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a> </p><p>The initial development was done in a couple of months, included the entire integer processing functionality of the instruction set; the bare minimum to make it compliant, with no <a href="/facts/Memory_management_unit/tJQtAQzI">memory management unit</a> (MMU) and no <a href="/facts/Floating-point_unit/XWTW2AbF">floating-point unit</a>.<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a> </p><p>Later additions to the implementation includes <a href="/facts/JTAG/IxRc5rG7">JTAG</a> debugger interface, divider instructions, 16 KB instruction and 32 KB data <a href="/facts/CPU_cache/x8BYFcdv">caches</a>, a non-hypervisor-capable MMU, <a href="/facts/Pipeline_(computing)/xmHjrPMP">pipelining</a><a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a> and <a href="/facts/Floating-point_unit/XWTW2AbF">floating-point</a> support.<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a> </p><p>It's designed using VHDL 2008 and the <a href="/facts/List_of_HDL_simulators/MnAsJPqd">GHDL simulation environment</a>.<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a> </p> <h3>Chiselwatt</h3> <p>A sibling project called Chiselwatt is another open processor core implementing the Power ISA 3.0 instruction set, written in the <a href="/facts/Scala_(programming_language)/ebL8o6AK">Scala</a>-based Chisel instead of VHDL.<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a><a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a> </p> <h2 id="implementations">Implementations</h2> <ul><li>Microwatt itself</li> <li><a href="/facts/Libre-SOC/uKm3wH7Y">Libre-SOC</a> – A <a href="/facts/Free_software/IaoVtJXn">libre</a> <a href="/facts/System_on_a_chip/1RVvVe6N">system on a chip</a> under development that uses Microwatt as a <a href="/facts/Reference_design/yowHlrsD">reference design</a>.<a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a></li> <li>Kestrel – A <a href="/facts/Soft_microprocessor/pCmb601M">soft</a> <a href="/facts/Intelligent_Platform_Management_Interface/hrcePUSL">BMC</a> in Raptor Engineering <a href="/facts/POWER9/1xMKJHsX">POWER9 based workstations</a>.<a class="footnote-ref" id="fnref:16" href="#fn:16"><sup>16</sup></a><a class="footnote-ref" id="fnref:17" href="#fn:17"><sup>17</sup></a></li></ul> <h2 id="history">History</h2> <p>It is the first processor written from scratch using the open Power ISA 3.0, and is released by the OpenPOWER Foundation as a reference design. </p><p>The project started as a demo, proof of concept and a reference implementation for the release of the opensource initiative regarding Power ISA 3.0.<a class="footnote-ref" id="fnref:18" href="#fn:18"><sup>18</sup></a> The goal for Blanchard was to see if he could make it, and as a software developer, taking on a very low level hardware project was a challenge.<a class="footnote-ref" id="fnref:19" href="#fn:19"><sup>19</sup></a><a class="footnote-ref" id="fnref:20" href="#fn:20"><sup>20</sup></a> </p><p>Microwatt is set to be <a href="/facts/Semiconductor_device_fabrication/Jd23Mu1z">fabricated</a> in <a href="/facts/130_nm_process/HXtpIErn">130 nm</a> by Efabless "Open MPW Shuttle Program" in 2021.<a class="footnote-ref" id="fnref:21" href="#fn:21"><sup>21</sup></a> As of February 2024, there has been no update on the progress of fabrication on Efabless's Microwatt project page.<a class="footnote-ref" id="fnref:22" href="#fn:22"><sup>22</sup></a> </p> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/OpenPOWER_Foundation/490VY6za">OpenPOWER Foundation</a></li> <li><a href="/facts/IBM_Power_microprocessors/twCjzqAx">IBM Power microprocessors</a></li></ul> <h2 id="external-links">External links</h2> <ul><li><a href="https://github.com/antonblanchard/microwatt">microwatt</a> on <a href="/facts/GitHub/n1hNCsc3">GitHub</a></li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>OpenPOWER Summit NA 2019: Day 2 Keynote Demonstration: Anton Blanchard, IBM & Joe DeLaere, Xilinx <a href="https://www.youtube.com/watch?v=JdMTLs7EMM0" target="_blank">https://www.youtube.com/watch?v=JdMTLs7EMM0</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>"POWER OpenISA and Microwatt introduction" - Anton Blanchard (LCA 2020) <a href="https://www.youtube.com/watch?v=RU6RPYAqFzE" target="_blank">https://www.youtube.com/watch?v=RU6RPYAqFzE</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>"Microwatt Microarchitecture" - Paul Mackerras (LCA 2020) <a href="https://www.youtube.com/watch?v=JkDx_y0onSk" target="_blank">https://www.youtube.com/watch?v=JkDx_y0onSk</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Microwatt and the POWER ISA support in Renode <a href="https://www.zephyrproject.org/microwatt-and-the-power-isa-support-in-renode/" target="_blank">https://www.zephyrproject.org/microwatt-and-the-power-isa-support-in-renode/</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Linux on Microwatt <a href="https://asciinema.org/a/331758" target="_blank">https://asciinema.org/a/331758</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>OpenPOWER opens further <a href="https://lwn.net/Articles/796796/" target="_blank">https://lwn.net/Articles/796796/</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Day 2 keynote and OpenPOWER blows the doors off: Royalty-free, open soft-core (RISC-V sweating gallons) <a href="https://www.talospace.com/2019/08/day-2-keynote-and-openpower-blows-doors.html" target="_blank">https://www.talospace.com/2019/08/day-2-keynote-and-openpower-blows-doors.html</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>"Microwatt Microarchitecture" - Paul Mackerras (LCA 2020) <a href="https://www.youtube.com/watch?v=JkDx_y0onSk" target="_blank">https://www.youtube.com/watch?v=JkDx_y0onSk</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>"Microwatt Microarchitecture" - Paul Mackerras (LCA 2020) <a href="https://www.youtube.com/watch?v=JkDx_y0onSk" target="_blank">https://www.youtube.com/watch?v=JkDx_y0onSk</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>"Microwatt Microarchitecture" - Paul Mackerras (LCA 2020) <a href="https://www.youtube.com/watch?v=JkDx_y0onSk" target="_blank">https://www.youtube.com/watch?v=JkDx_y0onSk</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>Microwatt Floats <a href="https://www.talospace.com/2020/09/microwatt-floats.html" target="_blank">https://www.talospace.com/2020/09/microwatt-floats.html</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>"POWER OpenISA and Microwatt introduction" - Anton Blanchard (LCA 2020) <a href="https://www.youtube.com/watch?v=RU6RPYAqFzE" target="_blank">https://www.youtube.com/watch?v=RU6RPYAqFzE</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p>Chiselwatt's page on Github <a href="https://github.com/antonblanchard/chiselwatt" target="_blank">https://github.com/antonblanchard/chiselwatt</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li> <li id="fn:14"><p>Final Draft of the Power ISA EULA Released <a href="https://openpowerfoundation.org/final-draft-of-the-power-isa-eula-released/" target="_blank">https://openpowerfoundation.org/final-draft-of-the-power-isa-eula-released/</a> <a href="#fnref:14" class="footnote-back-ref">↩</a></p></li> <li id="fn:15"><p>Libre-SOC <a href="https://libre-soc.org" target="_blank">https://libre-soc.org</a> <a href="#fnref:15" class="footnote-back-ref">↩</a></p></li> <li id="fn:16"><p>"Raptor Announces Kestrel Open-Source, Open HDL/Firmware Soft BMC". <a href="https://www.phoronix.com/scan.php?page=news_item&px=Raptor-Kestrel" target="_blank">https://www.phoronix.com/scan.php?page=news_item&px=Raptor-Kestrel</a> <a href="#fnref:16" class="footnote-back-ref">↩</a></p></li> <li id="fn:17"><p>Kestrel SoftBMC Project <a href="https://gitlab.raptorengineering.com/kestrel-collaboration/kestrel-litex/litex-boards/-/blob/master/README.md" target="_blank">https://gitlab.raptorengineering.com/kestrel-collaboration/kestrel-litex/litex-boards/-/blob/master/README.md</a> <a href="#fnref:17" class="footnote-back-ref">↩</a></p></li> <li id="fn:18"><p>Big Blue open sources POWER chip instruction set <a href="https://www.nextplatform.com/2019/08/20/big-blue-open-sources-power-chip-instruction-set/" target="_blank">https://www.nextplatform.com/2019/08/20/big-blue-open-sources-power-chip-instruction-set/</a> <a href="#fnref:18" class="footnote-back-ref">↩</a></p></li> <li id="fn:19"><p>OpenPOWER Summit NA 2019: Day 2 Keynote Demonstration: Anton Blanchard, IBM & Joe DeLaere, Xilinx <a href="https://www.youtube.com/watch?v=JdMTLs7EMM0" target="_blank">https://www.youtube.com/watch?v=JdMTLs7EMM0</a> <a href="#fnref:19" class="footnote-back-ref">↩</a></p></li> <li id="fn:20"><p>"POWER OpenISA and Microwatt introduction" - Anton Blanchard (LCA 2020) <a href="https://www.youtube.com/watch?v=RU6RPYAqFzE" target="_blank">https://www.youtube.com/watch?v=RU6RPYAqFzE</a> <a href="#fnref:20" class="footnote-back-ref">↩</a></p></li> <li id="fn:21"><p>"Open MPW metadata for Microwatt". Archived from the original on 2021-02-28. Retrieved 2021-03-30. <a href="https://web.archive.org/web/20210228091345/https://efabless.com/requests/77/project_metadata" target="_blank">https://web.archive.org/web/20210228091345/https://efabless.com/requests/77/project_metadata</a> <a href="#fnref:21" class="footnote-back-ref">↩</a></p></li> <li id="fn:22"><p>"Efabless". Efabless. Retrieved 2024-02-16. <a href="https://platform.efabless.com/projects/1165" target="_blank">https://platform.efabless.com/projects/1165</a> <a href="#fnref:22" class="footnote-back-ref">↩</a></p></li> </ol>