11 May 2015
Welcome to the BERI Processor release!
BERI ('Bluespec Extensible RISC Implementation') is an FPGA soft-core RISC processor implementing a 64-bit MIPS-like ISA and providing a large number of system peripherals. BERI is capable of running FreeBSD version 10.0 onwards. BERI is written in Bluespec System Verilog.
BERI is derived from a research project called CHERI ('Capability Hardware Enhanced RISC Instructions') at SRI International and the University of Cambridge. CHERI adds some extra features to the BERI core which can be selected with build flags - it also means much of the source tree refer to 'cheri' but are equally relevant to 'beri'. CHERI extends the ISA to include a 'capability coprocessor' supporting fine-grained in-address-space memory protection and scalable compartmentalisation. CHERI's ISA extensions and features are considered extremely experimental and are an active target of continuing research. Documentation for these ISA extensions may be found in the CHERI Architecture Document.
The primary BERI release targets the DE4 FPGA board from Terasic [1] which contains an Altera Stratix 4 GX230 FPGA. A port to Xilinx FPGAs as part of the NetFPGA 10G initiative is under way, but is not included in the current release.
This release includes targets for simulation of BERI1/2 and CHERI1/2 processors, and files for FPGA synthesis for the DE4 board.
To build BERI you will need a Bluespec licence: if you are an academic institution this is available under the Bluespec University Program [2].
[2] http://bluespec.com/university-program.html
Further instructions for configuring your environment and building can be found in the BERI Hardware Reference (see below).
Instructions for building and booting FreeBSD on BERI can be found in the BERI Software Reference. The CHERI Users' Guide describes the tools necessary to use the CHERI capability extensions.
The BERI/CHERI source tree is organised into the following structure:
| Path in tree | Function |
|---|---|
| cheri/trunk/ | The CHERI1 CPU design |
| cheri/trunk/sw/ | Software to run bare-metal, when not using the |
| miniboot primary bootloader
cheri2/trunk/ | The CHERI2 CPU design cherilibs/trunk/ | Common libraries across CHERI1/CHERI2; peripherals cheribsd/trunk/ | Miniboot, simulation boot loader cheritest/trunk/ | The CHERI instruction set testsuite
A small 'hello world' test program may be found in cheri/trunk/sw/. We separately distribute the BERI ISA-level test suite ('cheritest') and distributions of FreeBSD/beri and CheriBSD suitable to run on the BERI and CHERI designs. The former is an essentially unmodified version of FreeBSD, as platform-support code and device drivers have been upstreamed. The latter depends on experimental kernel, compiler, and userspace changes and is likely suitable only for those interested in capability-system research rather than a general-purpose FPGA soft-core processor.
We have separately distributed the following documents for BERI/CHERI users:
| Document | Description |
|---|---|
| CHERI Documentation Roadmap | Guide to other documents |
| BERI Hardware Reference | BERI hardware documentation, testing |
| BERI Software Reference | FreeBSD on BERI (and related topics) |
| CHERI Instruction-set Architecture | The CHERI security model and ISA |
| CHERI User's Guide | CHERI-specific software reference |
These can be downloaded via links from
http://www.beri-cpu.org/
We are aware of the following bug in this release, which has been fixed in SVN r18576 but the change has not yet passed through our release testing process:
CUnseal did not bounds-check the second capability argument which authorizes an unseal of a specified type. That is, a user possessing any capability to a type space (i.e. permit_seal is set) could construct an arbitrary out-of-bounds offset to describe any desired type and successfully unseal a capability of that type
BERI is licensed under the BERI Hardware-Software licence. See the BERI Open Systems CIC website for more information:
http://www.beri-open-systems.org/
A copy of the license has also been included with this distribution. If you submit patches to BERI, we will ask that you (and likely also your employing institution) sign and return BERI contribution agreements.
Further information is available on the BERI website: