2.2.1

Release notes

• add asynchronous message delivery
• add submodule ext/printf v4.0.0
• add FreeRTOS deep sleep
• add atomic mem access to peripherals
• move kernel runtime to ITIM to free 4KB RAM
• zone1: link with printf.c to reduce code size to < 128K
• zone2: link with printf.c and strtok.c to reduce code size < 16K
• fix -Wall and -Wextra warnings
• add prebuilt bitstreams for Arty A7 35T and 100T
• update riscv-gnu-toolchain-20210618 (rv32i|rv32e|rv64i)mac
• update riscv-openocd-20210807
• update manual.pdf and README.md

multizone.jar @1b9f31 (v2.2.1) / kernel @6b58e8 (v2.2.1):

• major redesign of kernel internal data structures
• up to 32/64 clint + 64/128 plic sources
• up to 256 clic sources for both rv32 and rv64
• reduce size of most kern vars from REGSIZE to 4-byte
• increase trap & emulation i-cache size
• add support for SiFive clic (E21)
• reintroduce support for rv32e 16-regs
• update riscv-gnu-toolchain-20210618 (rv32i|rv32e|rv64i)c