[RISC-V]1, How to Run Linux on RISC-V with QEMU Emulator

新ちゃん

Origin site:https://www.cnx-software.com/2018/03/16/how-to-run-linux-on-risc-v-with-qemu-emulator/

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RISC-V open source architecture is starting to become more and more interesting thanks the growing RISC-V hardware & software ecosystem, and with the recent release of HiFive Unleashed, we even have a board capable of running Linux. The only problem: it costs $999.

But luckily, it’s possible to experiment with Linux on RISC-V without extra hardware, just using your current PC. Imperas offers a commercial solution working on both Windows and Linux that relies on busybear-linux RISC-V Linux root filesystem comprised of busybox and dropbear SSH server. The rootfs also works with QEMU, so I tried it in Ubuntu 16.04.

The instructions on Github are quite easy to follow. My computer is powered by an AMD FX8350 processor coupled with 16GB RAM, and the whole process took around 2 hours, so better use the fastest computer possible. It also requires around 26 GB of storage on your build machine.

First, let’s create a working directory, and retrieve the RISC-V toolchain:

1. mkdir riscv-linux
   
2. cd riscv-linux/
   
3. git clone --recursive https://github.com/riscv/riscv-gnu-toolchain

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Now we can now build the RISC-V newlib & Linux toolchains) after installing some dependencies:

1. sudo apt-get install autoconf automake autotools-dev curl libmpc-dev libmpfr-dev libgmp-dev gawk build-essential bison flex texinfo gperf libtool patchutils bc zlib1g-dev libexpat-dev
   
2. cd riscv-gnu-toolchain
   
3. ./configure --prefix=/opt/riscv --enable-multilib
   
4. make newlib -j8
   
5. make linux -j8
   
6. export PATH=$PATH:/opt/riscv/bin
   
7. export RISCV=/opt/risc

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We’ll also need to build qemu for RISC-V

1. cd ..
   
2. git clone https://github.com/riscv/riscv-qemu.git
   
3. cd riscv-qemu
   
4. ./configure --target-list=riscv64-softmmu,riscv32-softmmu
   
5. make -j8
   
6. sudo make install

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The next three steps will build the rootfs, Linux 4.14 kernel, and the bootloader, but there are optional since you could just as well as download the binary releases.

• Build busybear-linux
  

1. cd ..
   
2. git clone https://github.com/michaeljclark/busybear-linux.git
   
3. cd busybear-linux
   
4. make -j8

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• Build RISC-V Linux
  

1. cd..
   
2. git clone https://github.com/riscv/riscv-linux.git
   
3. cd riscv-linux
   
4. git checkout riscv-linux-4.14
   
5. cp ../busybear-linux/conf/linux.config .config
   
6. make ARCH=riscv olddefconfig
   
7. make ARCH=riscv vmlinux -j8

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• Build BBL (Berkeley Boot Loader):
  
  

1. cd..
   
2. git clone https://github.com/riscv/riscv-pk.git
   
3. cd riscv-pk
   
4. mkdir build
   
5. cd build
   
6. ../configure --enable-logo --host=riscv64-unknown-elf --with-payload=../../riscv-linux/vmlinux
   
7. make -j8

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If we’re going to use the release files instead:

1. mkdir release
   
2. cd release
   
3. wget https://github.com/michaeljclark/busybear-linux/releases/download/v1.0/bbl.bz2
   
4. wget https://github.com/michaeljclark/busybear-linux/releases/download/v1.0/busybear.bin.bz2
   
5. bzip2 -d *.bz2

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You’d normally want to setup Linux bridged networking, and I tried, but failed and ran out of time. I added the following lines to /etc/network/interfaces in my computer:

1. iface br0 inet static
   
2.   bridge_ports eth0
   
3.   address 192.168.100.1
   
4.   netmask 255.255.255.0
   
5.   network 192.168.100.0
   
6.   broadcast 192.168.100.255

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and create two scripts in the current directory

• ifup
  

1. #!/bin/sh
   
2. 
   
3. brctl addif br0 $1
   
4. ifconfig $1 up

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• ifdown
  

1. #!/bin/sh
   
2. 
   
3. ifconfig $1 down
   
4. brctl delif br0 $1

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But I did not get it to work in a reasonable time. Studying QEMU Networking page on Arch Linux in details should help.

[Update: See comments’ section for SSH access using the Fedora RISC-V image instead]

Nevertheless I could still run Linux on RISC-V with QEMU using the following command:

1. sudo qemu-system-riscv64 -nographic -machine virt   -kernel bbl -append "root=/dev/vda ro console=ttyS0"   \
   
2. -drive file=busybear.bin,format=raw,id=hd0   -device virtio-blk-device,drive=hd0   \
   
3. -netdev type=tap,script=./ifup,downscript=./ifdown,id=net0   -device virtio-net-device,netdev=net0

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The boot takes just over one second to our minimal rootfs. Here’s the boot log:

1.               vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
   
2.                   vvvvvvvvvvvvvvvvvvvvvvvvvvvv
   
3. rrrrrrrrrrrrr       vvvvvvvvvvvvvvvvvvvvvvvvvv
   
4. rrrrrrrrrrrrrrrr      vvvvvvvvvvvvvvvvvvvvvvvv
   
5. rrrrrrrrrrrrrrrrrr    vvvvvvvvvvvvvvvvvvvvvvvv
   
6. rrrrrrrrrrrrrrrrrr    vvvvvvvvvvvvvvvvvvvvvvvv
   
7. rrrrrrrrrrrrrrrrrr    vvvvvvvvvvvvvvvvvvvvvvvv
   
8. rrrrrrrrrrrrrrrr      vvvvvvvvvvvvvvvvvvvvvv  
   
9. rrrrrrrrrrrrr       vvvvvvvvvvvvvvvvvvvvvv   
   
10. rr                vvvvvvvvvvvvvvvvvvvvvv      
    
11. rr            vvvvvvvvvvvvvvvvvvvvvvvv      rr
    
12. rrrr      vvvvvvvvvvvvvvvvvvvvvvvvvv      rrrr
    
13. rrrrrr      vvvvvvvvvvvvvvvvvvvvvv      rrrrrr
    
14. rrrrrrrr      vvvvvvvvvvvvvvvvvv      rrrrrrrr
    
15. rrrrrrrrrr      vvvvvvvvvvvvvv      rrrrrrrrrr
    
16. rrrrrrrrrrrr      vvvvvvvvvv      rrrrrrrrrrrr
    
17. rrrrrrrrrrrrrr      vvvvvv      rrrrrrrrrrrrrr
    
18. rrrrrrrrrrrrrrrr      vv      rrrrrrrrrrrrrrrr
    
19. rrrrrrrrrrrrrrrrrr          rrrrrrrrrrrrrrrrrr
    
20. rrrrrrrrrrrrrrrrrrrr      rrrrrrrrrrrrrrrrrrrr
    
21. rrrrrrrrrrrrrrrrrrrrrr  rrrrrrrrrrrrrrrrrrrrrr
    
22. 
    
23.        INSTRUCTION SETS WANT TO BE FREE
    
24. [    0.000000] OF: fdt: Ignoring memory range 0x80000000 - 0x80200000
    
25. [    0.000000] Linux version 4.14.0-00032-gd10799b22913-dirty (mclark@minty) (gcc version 7.1.1 20170509 (GCC)) #79 Sun Dec 17 10:41:31 NZDT 2017
    
26. [    0.000000] Zone ranges:
    
27. [    0.000000]   DMA      [mem 0x0000000080200000-0x0000000087ffffff]
    
28. [    0.000000]   Normal   empty
    
29. [    0.000000] Movable zone start for each node
    
30. [    0.000000] Early memory node ranges
    
31. [    0.000000]   node   0: [mem 0x0000000080200000-0x0000000087ffffff]
    
32. [    0.000000] Initmem setup node 0 [mem 0x0000000080200000-0x0000000087ffffff]
    
33. [    0.000000] elf_hwcap is 0x112d
    
34. [    0.000000] Built 1 zonelists, mobility grouping on.  Total pages: 31815
    
35. [    0.000000] Kernel command line: root=/dev/vda ro console=ttyS0
    
36. [    0.000000] PID hash table entries: 512 (order: 0, 4096 bytes)
    
37. [    0.000000] Dentry cache hash table entries: 16384 (order: 5, 131072 bytes)
    
38. [    0.000000] Inode-cache hash table entries: 8192 (order: 4, 65536 bytes)
    
39. [    0.000000] Sorting __ex_table...
    
40. [    0.000000] Memory: 122496K/129024K available (2658K kernel code, 216K rwdata, 652K rodata, 96K init, 782K bss, 6528K reserved, 0K cma-reserved)
    
41. [    0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
    
42. [    0.000000] NR_IRQS: 0, nr_irqs: 0, preallocated irqs: 0
    
43. [    0.000000] riscv,cpu_intc,0: 64 local interrupts mapped
    
44. [    0.000000] riscv,plic0,c000000: mapped 10 interrupts to 1/2 handlers
    
45. [    0.000000] clocksource: riscv_clocksource: mask: 0xffffffffffffffff max_cycles: 0x24e6a1710, max_idle_ns: 440795202120 ns
    
46. [    0.000000] Console: colour dummy device 80x25
    
47. [    0.000000] Calibrating delay loop (skipped), value calculated using timer frequency.. 20.00 BogoMIPS (lpj=100000)
    
48. [    0.000000] pid_max: default: 32768 minimum: 301
    
49. [    0.000000] Mount-cache hash table entries: 512 (order: 0, 4096 bytes)
    
50. [    0.000000] Mountpoint-cache hash table entries: 512 (order: 0, 4096 bytes)
    
51. [    0.090000] devtmpfs: initialized
    
52. [    0.110000] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
    
53. [    0.110000] futex hash table entries: 256 (order: 0, 6144 bytes)
    
54. [    0.110000] random: get_random_u32 called from bucket_table_alloc+0x80/0x1f6 with crng_init=0
    
55. [    0.110000] NET: Registered protocol family 16
    
56. [    0.140000] vgaarb: loaded
    
57. [    0.150000] clocksource: Switched to clocksource riscv_clocksource
    
58. [    0.170000] NET: Registered protocol family 2
    
59. [    0.170000] TCP established hash table entries: 1024 (order: 1, 8192 bytes)
    
60. [    0.170000] TCP bind hash table entries: 1024 (order: 1, 8192 bytes)
    
61. [    0.170000] TCP: Hash tables configured (established 1024 bind 1024)
    
62. [    0.180000] UDP hash table entries: 256 (order: 1, 8192 bytes)
    
63. [    0.180000] UDP-Lite hash table entries: 256 (order: 1, 8192 bytes)
    
64. [    0.180000] NET: Registered protocol family 1
    
65. [    0.190000] workingset: timestamp_bits=62 max_order=15 bucket_order=0
    
66. [    0.220000] random: fast init done
    
67. [    0.270000] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 254)
    
68. [    0.270000] io scheduler noop registered
    
69. [    0.270000] io scheduler deadline registered
    
70. [    0.270000] io scheduler cfq registered (default)
    
71. [    0.270000] io scheduler mq-deadline registered
    
72. [    0.270000] io scheduler kyber registered
    
73. [    0.380000] Serial: 8250/16550 driver, 4 ports, IRQ sharing disabled
    
74. [    0.390000] console [ttyS0] disabled
    
75. [    0.400000] 10000000.uart: ttyS0 at MMIO 0x10000000 (irq = 1, base_baud = 230400) is a 16550A
    
76. [    0.430000] console [ttyS0] enabled
    
77. [    0.480000] NET: Registered protocol family 10
    
78. [    0.490000] Segment Routing with IPv6
    
79. [    0.490000] sit: IPv6, IPv4 and MPLS over IPv4 tunneling driver
    
80. [    0.520000] EXT4-fs (vda): couldn't mount as ext3 due to feature incompatibilities
    
81. [    0.520000] EXT4-fs (vda): INFO: recovery required on readonly filesystem
    
82. [    0.530000] EXT4-fs (vda): write access will be enabled during recovery
    
83. [    0.610000] EXT4-fs (vda): recovery complete
    
84. [    0.620000] EXT4-fs (vda): mounted filesystem with ordered data mode. Opts: (null)
    
85. [    0.630000] VFS: Mounted root (ext4 filesystem) readonly on device 254:0.
    
86. [    0.630000] devtmpfs: mounted
    
87. [    0.640000] Freeing unused kernel memory: 96K
    
88. [    0.640000] This architecture does not have kernel memory protection.
    
89. [    0.970000] EXT4-fs (vda): re-mounted. Opts: data=ordered
    
90. 
    
91. ucbvax login:

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We can login with root using password “busybear” without quote.

1. ucbvax login: root
   
2. Password:
   
3.     ____                   ____                     __    _                 
   
4.    / __ )__  _________  __/ __ )___  ____ ______   / /   (_)___  __  ___  __
   
5.   / __  / / / / ___/ / / / __  / _ \/ __ `/ ___/  / /   / / __ \/ / / / |/_/
   
6. / /_/ / /_/ (__  ) /_/ / /_/ /  __/ /_/ / /     / /___/ / / / / /_/ />  <  
   
7. /_____/\__,_/____/\__, /_____/\___/\__,_/_/     /_____/_/_/ /_/\__,_/_/|_|  
   
8.                  /____/                                                     
   
9. root@ucbvax:~# uname -a
   
10. Linux ucbvax 4.14.0-00032-gd10799b22913-dirty #79 Sun Dec 17 10:41:31 NZDT 2017 riscv64 GNU/Linux
    
11. root@ucbvax:~# df -h
    
12. Filesystem                Size      Used Available Use% Mounted on
    
13. /dev/root                58.0M     44.9M      8.6M  84% /
    
14. devtmpfs                 59.8M         0     59.8M   0% /dev
    
15. none                     59.9M         0     59.9M   0% /tmp
    
16. none                     59.9M         0     59.9M   0% /var/tmp
    
17. root@ucbvax:~# cat /proc/cpuinfo
    
18. hart        : 0
    
19. isa        : rv64imafdcsu
    
20. mmu        : sv48
    
21. 
    
22. root@ucbvax:~# busybox
    
23. BusyBox v1.27.2 (2017-12-15 12:14:50 NZDT) multi-call binary.
    
24. BusyBox is copyrighted by many authors between 1998-2015.
    
25. Licensed under GPLv2. See source distribution for detailed
    
26. copyright notices.
    
27. 
    
28. Usage: busybox [function [arguments]...]
    
29.    or: busybox --list[-full]
    
30.    or: busybox --install [-s] [DIR]
    
31.    or: function [arguments]...
    
32. 
    
33.         BusyBox is a multi-call binary that combines many common Unix
    
34.         utilities into a single executable.  Most people will create a
    
35.         link to busybox for each function they wish to use and BusyBox
    
36.         will act like whatever it was invoked as.
    
37. 
    
38. Currently defined functions:
    
39.         [, [[, add-shell, addgroup, adduser, ar, arp, arping, ash, awk, base64,
    
40.         basename, blkid, blockdev, brctl, bunzip2, bzcat, bzip2, cal, cat,
    
41.         chattr, chgrp, chmod, chown, chpasswd, chroot, chrt, cksum, clear,
    
42.         comm, cp, cpio, crond, crontab, cut, date, dd, delgroup, deluser, df,
    
43.         diff, dirname, dmesg, dos2unix, dpkg, dpkg-deb, du, echo, ed, egrep,
    
44.         env, expand, expr, factor, fallocate, false, fdisk, fgrep, find,
    
45.         findfs, flock, fold, fsck, fsfreeze, fsync, fuser, getty, grep, groups,
    
46.         gunzip, gzip, halt, head, hostid, hostname, id, ifconfig, ifdown, ifup,
    
47.         inetd, init, install, iostat, ip, ipaddr, iplink, ipneigh, iproute,
    
48.         iprule, iptunnel, kill, killall, klogd, last, less, link, ln, logger,
    
49.         login, logname, logread, losetup, ls, lsattr, lsof, lspci, lsscsi,
    
50.         lsusb, lzcat, lzma, makedevs, man, md5sum, microcom, mkdir, mkdosfs,
    
51.         mke2fs, mkfifo, mkfs.ext2, mkfs.vfat, mknod, mkpasswd, mkswap, mktemp,
    
52.         more, mount, mv, nameif, nc, netstat, nice, nl, nohup, nproc, nslookup,
    
53.         ntpd, od, partprobe, passwd, paste, patch, pgrep, pidof, ping, ping6,
    
54.         pipe_progress, pivot_root, pkill, pmap, poweroff, printenv, printf, ps,
    
55.         pstree, pwd, pwdx, rdev, readlink, realpath, reboot, remove-shell,
    
56.         renice, reset, rev, rm, rmdir, route, rpm, rpm2cpio, run-parts,
    
57.         runlevel, script, sed, seq, setpriv, setserial, setsid, sh, sha1sum,
    
58.         sha256sum, sha3sum, sha512sum, shred, shuf, sleep, sort, split,
    
59.         ssl_client, start-stop-daemon, stat, strings, stty, su, sum, swapoff,
    
60.         swapon, switch_root, sync, sysctl, syslogd, tac, tail, tar, taskset,
    
61.         tee, telnet, test, time, timeout, top, touch, tr, traceroute,
    
62.         traceroute6, true, truncate, tty, tunctl, tune2fs, udhcpc, uevent,
    
63.         umount, uname, uncompress, unexpand, uniq, unix2dos, unlink, unlzma,
    
64.         unshare, unxz, unzip, uptime, users, usleep, uudecode, uuencode, vi, w,
    
65.         wall, watch, wc, wget, which, who, whoami, whois, xargs, xxd, xz,
    
66.         xzcat, yes, zcat

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Type halt to turn off Linux and QEMU:

1. root@ucbvax:~# halt
   
2. root@ucbvax:~# umount: devtmpfs busy - remounted read-only
   
3. umount: can't remount /dev/root read-only
   
4. The system is going down NOW!
   
5. Sent SIGTERM to all processes
   
6. Sent SIGKILL to all processes
   
7. Requesting system halt
   
8. [  410.790000] reboot: System halted
   
9. Power off

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