尝试在RISC-V Rocket芯片上移植Linux内核

Question

We have looked the u-boot support from www.denx.de webpage, but we could not able find support for RISC-V. So where can we find the u-boot support for RISC-V chip.

The "www.lowrisc.org" web page says RISC-V should use BBL (Berkeley bootloader) for loading the Linux kernel. We are not clear about the process for developing the BBL based boot image, since it required FSBL (first stage bootloader) image development and the FSBL is associated to Vivado SDK.

Note: Bootloader which we are looking for is not for simulation

Answer 1

There is message in the mailing list from 14 Feb 2017 about u-boot for risc-v: https://groups.google.com/a/groups.riscv.org/forum/#!topic/sw-dev/j63wzz2ylY8

U-Boot port on RISC-V 32-bit is available on github.

https://github.com/Microsemi-SoC-IP/RISC-V_U-Boot

This repository contains the U-Boot port by Microsemi for RISC-V core on Smartfusion2 M2Sxxx devices. The Smartfusion2 M2S150 FPGA Advance Dev Kit is used for RISC-V U-Boot and the FPGA design available at RISCV-on-Microsemi-FPGA.

The site of this project is https://github.com/Microsemi-SoC-IP/RISC-V_U-Boot

Development repository for RISC-V U-Boot on Microsemi FPGA

This repository contains the U-Boot created by Microsemi for RISC-V core on Smartfusion2 M2Sxxx devices. The Smartfusion2 M2S150 FPGA Advance Dev Kit is used for RISC-V U-Boot and the FPGA design available at RISCV-on-Microsemi-FPGA.

PS: FSBL is specific to Xilinx SoC "Zynq"; but BBL itself should be independent from FPGA vendor. Check also Untethered lowRISC : http://www.lowrisc.org/blog/2015/12/untethered-lowrisc-release/ http://www.lowrisc.org/docs/untether-v0.2/ . Second page has http://www.lowrisc.org/docs/untether-v0.2/bootload/ about boot process and BBL just should be copied to RAM by risc-v "first stage bootloader" ( $TOP/fpga/board/$FPGA_BOARD/examples/boot.c ) in case of Untethered (this is not FSBL of Zynq); then risc-v "first stage bootloader" will do softreset to restart cpu from BBL which will load linux kernel.