boot0-riscv

0-stage loader with relocation and lzma/lz4 decompression of payload. Does not access any CSRs and does not use priviledge instructions. Works in any priviledge mode. The one hart selected by lottery does relocation and decompression. The rest harts jump to payload after boot hart has finished his work.

Getting started

$ make
CROSS_COMPILE=/opt/riscv-gcc/bin/riscv64-unknown-elf-
COMPRESS_ALGO="lz4"
RISCV_XLEN=64
FW_PAYLOAD_PATH=/home/avx/xv6-riscv/kernel/kernel.bin
FW_PAYLOAD_CRC32=0
FW_LOAD_ADDR=0x80200000
FW_START_ADDR=0x80200000
FW_OUT_BIN=./z_kernel.bin

Build parameters

• FW_LOAD_ADDR : address where the payload should be loaded in memory
• FW_START_ADDR : address of entry point of payload. Equal to FW_LOAD_ADDR if not specified explicitly.
• FW_PAYLOAD_CRC32=1 for runtime crc32 check of decompressed payload
• COMPRESS_ALGO="lzma" : lzma algorithm (better compression)
• COMPRESS_ALGO="lz4" : lz4 algorithm (fast decompress)
• COMPRESS_ALGO="none" : no compression is used, just relocation of payload

QEMU

qemu-system-riscv64 ... -smp 4 --accel tcg,thread=single

IMPORTANT

lzma from lzma packages is required, not xz-lzma

$ lzma -h

lzma 9.22 Copyright (C) 2006 Ville Koskinen Based on LZMA SDK 9.22 Copyright (C) 1999-2011 Igor Pavlov

Examples

• rv64, lzma, crc32, vmlinux.bin:

payload            : 17619456 bytes
compressed payload : 4001639 bytes
boot0+comp.payload : 4008872 bytes
boot0              : 7233 bytes

• rv64, lz4, vmlinux.bin:

payload            : 17619456 bytes
compressed payload : 5472395 bytes
boot0+comp.payload : 5474208 bytes
boot0              : 1813 bytes