Running 32-bit Linux on LiteX/VexRiscv on Avalanche board with Microsemi PolarFire FPGA
This section contains a tutorial on how to build and run 32-bit Linux on the LiteX soft SoC with an RV32 VexRiscv CPU on the Future Electronics Avalanche Board with a PolarFire FPGA from Microsemi (a Microchip company) as well as in the Renode open source simulation framework.
Fig. 4 The Future Electronics Avalanche board - top.
Note
This chapter targets Debian-based Linux flavors, and has been tested on Ubuntu 18.04.
Prerequisites
Running Linux on the Litex/VexRiscv platform requires you to install some prerequisites.
sudo apt install autoconf automake autotools-dev bc bison build-essential curl cpio flex \
gawk gdisk git gperf libgmp-dev libmpc-dev libmpfr-dev libncurses-dev \
libssl-dev libtool patchutils python rsync screen texinfo unzip zlib1g-dev
Getting the sources
Clone the official Buildroot repository and apply a patch adding VexRiscv support
git clone https://github.com/buildroot/buildroot
cd buildroot
git checkout 653bf9383721a2e2d3313ae08a3019b864326
git am ../../files/0001-Add-Litex-VexRiscv-support.patch
Building
Simply run:
mkdir ~/vexriscv-bins
make litex_vexriscv_defconfig
make -j`nproc`
cp output/images/Image output/images/rootfs.cpio ~/vexriscv-bins
Note
The build process may take some time, do not be discouraged by the wait. The resulting binaries (rootfs.cpio and Image) will be written in the output/images folder.
Running
Preparing the platform
Loading Linux images
First, download pre-built binaries of two files needed for running Linux on the platform, the Machine Mode emulator and the device tree:
cd ~/vexriscv-bins
wget https://github.com/riscv/risc-v-getting-started-guide/releases/download/tip/devicetree-litex-vexriscv-avalanche-linux.dtb
wget https://github.com/riscv/risc-v-getting-started-guide/releases/download/tip/emulator-litex-vexriscv-avalanche-linux.bin
Running Linux
Now you should see the following log of booting Linux:
VexRiscv Machine Mode software built May 13 2019 14:14:12
--========== Booting Linux =============--
[ 0.000000] No DTB passed to the kernel
[ 0.000000] Linux version 5.0.14 (user@host) (gcc version 8.3.0 (Buildroot 2019.05-rc1-00022-g653bf93)) #1 Mon May 13 10:22:15 CEST 2019
[ 0.000000] Initial ramdisk at: 0x(ptrval) (8388608 bytes)
[ 0.000000] Zone ranges:
[ 0.000000] Normal [mem 0x00000000c0000000-0x00000000c7ffffff]
[ 0.000000] Movable zone start for each node
[ 0.000000] Early memory node ranges
[ 0.000000] node 0: [mem 0x00000000c0000000-0x00000000c7ffffff]
[ 0.000000] Initmem setup node 0 [mem 0x00000000c0000000-0x00000000c7ffffff]
[ 0.000000] elf_hwcap is 0x1101
[ 0.000000] Built 1 zonelists, mobility grouping on. Total pages: 32512
[ 0.000000] Kernel command line: mem=128M@0x40000000 rootwait console=hvc0 root=/dev/ram0 init=/sbin/init swiotlb=32
[ 0.000000] Dentry cache hash table entries: 16384 (order: 4, 65536 bytes)
[ 0.000000] Inode-cache hash table entries: 8192 (order: 3, 32768 bytes)
[ 0.000000] Sorting __ex_table...
[ 0.000000] Memory: 119052K/131072K available (1958K kernel code, 90K rwdata, 317K rodata, 104K init, 184K bss, 12020K reserved, 0K cma-reserved)
[ 0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
[ 0.000000] NR_IRQS: 0, nr_irqs: 0, preallocated irqs: 0
[ 0.000000] clocksource: riscv_clocksource: mask: 0xffffffffffffffff max_cycles: 0x114c1bade8, max_idle_ns: 440795203839 ns
[ 0.000751] sched_clock: 64 bits at 75MHz, resolution 13ns, wraps every 2199023255546ns
[ 0.006686] Console: colour dummy device 80x25
[ 0.205255] printk: console [hvc0] enabled
[ 0.213843] Calibrating delay loop (skipped), value calculated using timer frequency.. 150.00 BogoMIPS (lpj=300000)
[ 0.230054] pid_max: default: 32768 minimum: 301
[ 0.289177] Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.300773] Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.562839] devtmpfs: initialized
[ 0.777903] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 7645041785100000 ns
[ 0.793367] futex hash table entries: 256 (order: -1, 3072 bytes)
[ 1.514347] clocksource: Switched to clocksource riscv_clocksource
[ 2.964577] Unpacking initramfs...
[ 11.940415] Initramfs unpacking failed: junk in compressed archive
[ 12.049860] workingset: timestamp_bits=30 max_order=15 bucket_order=0
[ 13.575690] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 254)
[ 13.588037] io scheduler mq-deadline registered
[ 13.593169] io scheduler kyber registered
[ 22.876345] random: get_random_bytes called from init_oops_id+0x4c/0x60 with crng_init=0
[ 23.017785] Freeing unused kernel memory: 104K
[ 23.025710] This architecture does not have kernel memory protection.
[ 23.036765] Run /init as init process
mount: mounting tmpfs on /dev/shm failed: Invalid argument
mount: mounting tmpfs on /tmp failed: Invalid argument
mount: mounting tmpfs on /run failed: Invalid argument
Starting syslogd: OK
Starting klogd: OK
Initializing random number generator... [ 36.389928] random: dd: uninitialized urandom read (512 bytes read)
done.
Starting network: ip: socket: Function not implemented
ip: socket: Function not implemented
FAIL
Welcome to Buildroot
buildroot login: root
__ _ __ _ __ _ __ _ __ ___ _
/ / (_)__ __ ____ _________ ___ ____/ / (_) /____ | |/_/__| | / /____ __ / _ \(_)__ _____ __
/ /__/ / _ \/ // /\ \ /___/ _ \/ _ \/___/ /__/ / __/ -_)> </___/ |/ / -_) \ // , _/ (_-</ __/ |/ /
/____/_/_//_/\_,_//_\_\ \___/_//_/ /____/_/\__/\__/_/|_| |___/\__/_\_\/_/|_/_/___/\__/|___/
32-bits VexRiscv CPU with MMU integrated in a LiteX SoC
login[48]: root login on 'hvc0'
root@buildroot:~#
The default Linux credentials are:
- username
root
- password
(no pass)