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opensecura / 3p / lowrisc / opentitan / cb56b467022a58683cdbf5589cc7a8a7c15944a6
commitcb56b467022a58683cdbf5589cc7a8a7c15944a6[log] [tgz]
authorPirmin Vogel <vogelpi@lowrisc.org>Tue Jan 04 19:00:40 2022 +0100
committerPirmin Vogel <vogelpi@lowrisc.org>Thu Jan 06 15:23:58 2022 +0100
treebad84c4962177d4e98c5e586f635c2351d37ff95
parent8cfa6f20022a9b7e2f5379c06520bc02e63fb4bd [diff]
[prim_xilinx] Replace KEEP with DONT_TOUCH attributes

Previously, we have been using KEEP attributes to prevent synthesis
optimizations across these primitives to ensure that FI and SCA
countermeasures are not optimized away. However, according to the
Vivado Design Suite User Guide: Synthesis (UG901), the KEEP attribute
is commonly used in conjunction with timing constraints but
doesn't force place and route to keep the signal. Instead, the
DONT_TOUCH attribute is recommended for this purpose (see Chapter 2):

"Unlike KEEP and KEEP_HIERARCHY, DONT_TOUCH is forward-annotated to
place and route to prevent logic optimization."

In addition, the KEEP/DONT_TOUCH attributes are not supported on ports
of modules and instead should be applied to the module itself.

Signed-off-by: Pirmin Vogel <vogelpi@lowrisc.org>
5 files changed
tree: bad84c4962177d4e98c5e586f635c2351d37ff95
  1. .github/
  2. ci/
  3. doc/
  4. hw/
  5. rules/
  6. site/
  7. sw/
  8. test/
  9. third_party/
  10. util/
  11. .bazelignore
  12. .bazelrc
  13. .bazelversion
  14. .clang-format
  15. .dockerignore
  16. .flake8
  17. .gitignore
  18. .style.yapf
  19. .svlint.toml
  20. .svls.toml
  21. _index.md
  22. apt-requirements.txt
  23. azure-pipelines.yml
  24. BUILD
  25. check_tool_requirements.core
  26. CLA
  27. COMMITTERS
  28. CONTRIBUTING.md
  29. LICENSE
  30. meson.build
  31. meson_init.sh
  32. meson_options.txt
  33. python-requirements.txt
  34. README.md
  35. tool_requirements.py
  36. toolchain.txt
  37. topgen-reg-only.core
  38. topgen.core
  39. WORKSPACE
  40. yum-requirements.txt
README.md

OpenTitan

OpenTitan logo

About the project

OpenTitan is an open source silicon Root of Trust (RoT) project. OpenTitan will make the silicon RoT design and implementation more transparent, trustworthy, and secure for enterprises, platform providers, and chip manufacturers. OpenTitan is administered by lowRISC CIC as a collaborative project to produce high quality, open IP for instantiation as a full-featured product. See the OpenTitan site and OpenTitan docs for more information about the project.

About this repository

This repository contains hardware, software and utilities written as part of the OpenTitan project. It is structured as monolithic repository, or “monorepo”, where all components live in one repository. It exists to enable collaboration across partners participating in the OpenTitan project.

Documentation

The project contains comprehensive documentation of all IPs and tools. You can access it online at docs.opentitan.org.

How to contribute

Have a look at CONTRIBUTING and our documentation on project organization and processes for guidelines on how to contribute code to this repository.

Licensing

Unless otherwise noted, everything in this repository is covered by the Apache License, Version 2.0 (see LICENSE for full text).