From ad570000b3867a8bc10a9b811c7fd2a59d421b4e Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?J=C3=A9r=C3=B4me=20Qu=C3=A9vremont?= Date: Fri, 15 Dec 2023 14:52:10 +0100 Subject: [PATCH] Remove fixed-time division (ISA-110) (#1670) After further investigation, the feature is not needed for security application. For safety applications, variable-time division is only one of several sources of unpredictability and it does not make no real sense to fix it. --- .../cva6_requirements_specification.rst | 13 ------------- 1 file changed, 13 deletions(-) diff --git a/docs/02_cva6_requirements/cva6_requirements_specification.rst b/docs/02_cva6_requirements/cva6_requirements_specification.rst index d7d1db1ab0..4f6d46c4a8 100644 --- a/docs/02_cva6_requirements/cva6_requirements_specification.rst +++ b/docs/02_cva6_requirements/cva6_requirements_specification.rst @@ -303,16 +303,6 @@ independent requirements. | | **Zifencei** extension, version | | | 2.0. | +-----------------------------------+-----------------------------------+ -| ISA‑110 | | As an **option**, the duration | -| | of instructions shall be | -| | independent from the operand | -| | values. | -| | | *Unlike other options, this one | -| | can be design-time (selected | -| | before compiling the RTL) or | -| | run-time (selected through a | -| | register).* | -+-----------------------------------+-----------------------------------+ | ISA-120 | CVA6 should support as an | | | **option** the **Zba**, **Zbb**, | | | **Zbc** and **Zbs** extensions | @@ -332,9 +322,6 @@ independent requirements. Note to ISA-60 and ISA-70: CV64A6 cannot support the D extension with the F extension. -Note to ISA-110: In the current design, the duration of the division -is data-dependent, which can be a security issue. - .. _privileges_and_virtual_memory: Privileges and virtual memory