xv6-mars

An attempt to port xv6-riscv to the MilkV mars SBC. As MilkV mars is based on JH7110, xv6-mars may be runnable on VisionFive2 or Star64 SBCs.

Important

This project is still under development.

Features

Feature	MilkV Mars specific
SBI timers	No
SBI HSM (start)	No
RamDisk	No
UART	Yes (config differs)
Buddy Allocator	No
Multilevel Queue Scheduling	No
CPU Temperature Sensor	Yes

Run

Configuration

You need to configure the kernel to run on the Mars board. Edit config.mk:

PLATFORM = mars

Build

To get xv6 starting on the board, you need to load manually everything. compile the kernel and ramdisk image

make
make fs.img

Tip

Connect to UART to get output:

Pin	GPIO
GND	6
Tx	8
Rx	10

Load

SD card

Copy kernel and fs.img to the mars SD card and then boot the mars.

Then once U-Boot prompt appears:

load mmc 1 ${loadaddr} kernel
load mmc 1 0x49000000 fs.img
bootelf ${loadaddr}

TFTP server

You can setup a DHCP and TFTP server and connect the Mars in the LAN. Then setup U-Boot:

setenv bootcmd='dhcp; tftpboot ${loadaddr} kernel; tftpboot 0x49000000 fs.img; bootelf ${loadaddr};'
saveenv

Debug

You can debug the kernel with GDB via OpenOCD on a JTAG port I found on the board.

JTAG Port	Mars GPIO Pin
TMS	35
TRSTN	36
TCK	37
TDI	38
TDO	40

Tip

Load kernel.sym in GDB to get sources