abstractaccelerator/release-notes.md

SweRV RISC-V Core^TM 1.5 from Western Digital

Release Notes

This is a bug-fix and performance-improvement release. No new functionality is added to the SweRV core.

1. Bug fixes:

• Hart incorrectly cleared dmcontrol.dmactive on reset (reported by Codasip). Note that a separate system power-on-reset signal dbg_rst_l was added to differentiate power-on-reset vs core reset.
• Hart never asserted the dmstatus.allrunning signal on reset which caused a timeout in OpenOCD (reported by Codasip).
• Debug module failed to auto-increment register on system-bus access of size 64-bit (reported by Codasip).
• The core_rst_n signal was incorrectly connected (reported by Codasip).
• Module/instance renamed for tool compatibility.
• The program counter was getting corrupted when the load/store unit indicated both a single-bit and a double-bit error in the same cycle.
• The MSTATUS register was not being updated as expected when both a non-maskable-interrupt and an MSTATUS-write happened in the same cycle.
• Write to SBDATA0 was not starting a system-bus write access when sbreadonaddr/sbreadondata is set.
• Minstret was incorrectly counting ecall/ebreak instructions.
• The dec_tlu_mpc_halted_only signal was not set for MPC halt after reset.
• The MEPC register was not being updated when a firmware-halt request was followed by a timer interrupt.
• The MINSTRETH control register was being incremented when performance counters were disabled.
• Bus driver contained combinational logic from multiple clock domains that sometimes caused a glitch.
• System bus reads were always being made with 64-bit size for the AXI bus which is incorrect for IO access.
• DCCM single-bit errors were counted for instructions that did not commit.
• ICCM single bit errors were double-counted.
• Load/store unit was not detecting access faults when DCCM and PIC memories are next to each other.
• Single-bit ECC errors on data load were not always corrected in the DCCM.
• Single-bit ECC errors were not always corrected in the DCCM for DMA accesses.
• Single-bit errors detected while reading ICCM through DMA were not being corrected in memory.

2. Improvements:

• Improved performance by removing redundant term in decode stall logic.
• Reduced power used by the ICCM memory arrays.

3. Testbench Improvements:

• AXI4 and AHB-Lite support.
• Updated bus memory to be persistent and handle larger programs.
• Makefile supports ability to run with source or pre-generated hex files.
• Makefile supports targets for CoreMarks benchmark (issue #25).
• Questa support in Makefile (Issue #19).

SweRV RISC-V Core^TM 1.4 from Western Digital

Release Notes

Move declarations to top of Verilog file to fix fpga compile issues.

SweRV RISC-V Core^TM 1.3 from Western Digital

Release Notes

1. Make the FPGA optimization code work with the latest version of Verilator.Pull request #13
2. Move JTAG TAP to swerv_wrapper module. Pull request #10

SweRV RISC-V Core^TM 1.2 from Western Digital

Release Notes

1. SWERV core RISCV compatibility improvements

   • The ebreak and ecall instructions are no longer counted in the MINSRET control and status register.
   • Write to SBDATA0 does not start SB write access when both sbreadonaddr/sbreadondata are zero. This fixes issue number 5 on github.

2. FPGA support: Add fpga_optimize option to swerv.config which eliminates over 90% of clock-gating enabling faster FPGA simulation.

3. Usability: Untabified all the verilog files. This fixes issue number 3 on github.

SweRV RISC-V Core^TM 1.1 from Western Digital

Release Notes

1. SWERV core RISCV compatibility improvements

   • Illegal instructions no longer increment minstret
   • Debug single-step command no longer executes multiple instructions
   • For instructions, MTVAL register holds the address that actually triggered an access fault
   • DICAD1 debug CSR ECC read size enhancements

2. SWERV core performance enhancements

   • Improved instruction fetch unit external memory access performance
   • Instruction fetcher no longer stalls due to DMA ICCM requests
   • Improved performance of streaming stores
   • Improved performance of divide instruction
   • Improved I/O Timing
   • Non-idempotent Ld/St changed to non-posted in MFDC
   • DMA QoS Configurable in MFDC

3. SWERV core miscellaneous changes

   • Non-word access to PIC memory generates access-error
   • Improved streaming performance with unified read/write buffer
   • Non-idempotent load enhancements
   • Debug, single-step, and trigger enhancements
   • DMA, IFU, and LSU interaction enhancements
   • Bus error handling improvements
   • DMA h-ready addition
   • DMA slave error response enhancements

4. Added memory protection windows

   • Now able to define up to eight instruction fetch windows and up to eight data load/store windows. See the programmer reference manual for more details.