构建riscv上运行的linux系统

  在qemu上启动linux kernel

 总述

最终目标还是要在RTL上跑linux系统，但做这个之前第一步先把系统工具链整清楚很重要，所以先在qemu上把相关的工具链，镜像搞定。

为了完全这项任务，我们需要安装几个工具， qemu for riscv,   linux kernel,  boot loader, toolbox

level	endcoding	Name	Abbreviation
0	00	User/Application	U
1	01	Supervisor	S
2	10	Reserved
3	11	Machine	M

如上图所示，  riscv包含3个特权等级，OS运行在Superviosr级上， bootloader和其他固件运行在Machine级上， 用户程序运行在User级上。

 工作目录

首先我们建立一个工作目录

mkdir riscv-linux

cd riscv-linux

 安装qemu for riscv

我们统一选项只安装64版本, 目录到和riscv toolschian相同目录里

git clone https://github.com/qemu/qemu

cd qemu

git checkout v5.0.0

./configure --target-list=riscv64-softmmu --prefix=${RISCV}

make

make install

编译生成linux kernel

回到工作目录riscv-linux

git clone https://github.com/torvalds/linux

cd linux

git checkout v5.4

make ARCH=riscv CROSS_COMPILE=riscv64-unknown-linux-gnu- defconfig

make ARCH=riscv CROSS_COMPILE=riscv64-unknown-linux-gnu-

生成的kernel image在arch/riscv/boot/Image

SBI

SBI 是 RISC-V Supervisor Binary Interface的简称， 它是一个中间接口：

• firmware和bootloader， OS之间的接口
• 一个Hypervisor和bootloader或运行在VS-mode下的OS之间的接口

cd opensbi

make PLATFORM=generic CROSS_COMPILE=riscv64-unknown-linux-gnu- PLATFORM_RISCV_XLEN=64 FW_PAYLOAD_PATH=../linux/arch/riscv/boot/Image

生成的bin文件在./build/platform/generic/firmware/fw_jump.bin

 生成busybox并制作文件系统

git clone https://git.busybox.net/busybox

cd busybox

CROSS_COMPILE=riscv{{bits}}-unknown-linux-gnu- make menuconfig

# 打开配置菜单后进入第一行的 "Settings"，在"Build Options"节中，选中 “Build static binary (no shared libs)”，设置好后退出保存配置

CROSS_COMPILE=riscv{{bits}}-unknown-linux-gnu- make

make install

# 源码目录 busyboxsource 下新出现一个 _install 目录 ，可以看到生成的东西

下面我们就要制作最小文件系统

qemu-img create rootfs.img  1g

mkfs.ext4 rootfs.img

mkdir rootfs

sudo mount -o loop rootfs.img  rootfs

cd rootfs

sudo cp -r ../busyboxsource/_install/* .

sudo mkdir proc sys dev etc etc/init.d

cd etc/init.d/

sudo touch rcS

sudo vi rcS

编译内容如下：

#!/bin/sh

mount -t proc none /proc

mount -t sysfs none /sys

/sbin/mdev -s

然后修改文件权限

sudo mod +x rcS

sudo umount rootfs

至此文件系统就制作完成了

 启动

回到riscv-linux目录， 执行下面命令立即就打印相关启动信息

qemu-system-riscv64 -M virt -m 256M -nographic -bios opensbi/build/platform/generic/firmware/fw_jump.bin -kernel ./linux/arch/riscv/boot/Image -drive file=./rootfs.img,format=raw,id=hd0  -device virtio-blk-device,drive=hd0 -append "root=/dev/vda rw console=ttyS0"

下面是打印的信息， 暂停时输入回车就进行了熟悉的shell命令行下。

# harriszh @ pc-harriszh2 in /trunk/branch/riscv [20:44:07] 

$ qemu-system-riscv64 -M virt -m 256M -nographic -bios opensbi/build/platform/generic/firmware/fw_jump.bin -kernel ./linux/arch/riscv/boot/Image -drive file=./rootfs.img,format=raw,id=hd0  -device virtio-blk-device,drive=hd0 -append "root=/dev/vda rw console=ttyS0"

OpenSBI v0.8-58-g781cafd

   ____                    _____ ____ _____

  / __                   / ____|  _ _   _|

 | |  | |_ __   ___ _ __ | (___ | |_) || |

 | |  | | '_  / _  '_  ___ |  _ < | |

 | |__| | |_) |  __/ | | |____) | |_) || |_

  ____/| .__/ ___|_| |_|_____/|____/_____|

        | |

        |_|

Platform Name             : riscv-virtio,qemu

Platform Features         : timer,mfdeleg

Platform HART Count       : 1

Firmware Base             : 0x80000000

Firmware Size             : 108 KB

Runtime SBI Version       : 0.2

Domain0 Name              : root

Domain0 Boot HART         : 0

Domain0 HARTs             : 0*

Domain0 Region00          : 0x0000000080000000-0x000000008001ffff ()

Domain0 Region01          : 0x0000000000000000-0xffffffffffffffff (R,W,X)

Domain0 Next Address      : 0x0000000080200000

Domain0 Next Arg1         : 0x0000000082200000

Domain0 Next Mode         : S-mode

Domain0 SysReset          : yes

Boot HART ID              : 0

Boot HART Domain          : root

Boot HART ISA             : rv64imafdcsu

Boot HART Features        : scounteren,mcounteren,time

Boot HART PMP Count       : 16

Boot HART PMP Granularity : 4

Boot HART PMP Address Bits: 54

Boot HART MHPM Count      : 0

Boot HART MHPM Count      : 0

Boot HART MIDELEG         : 0x0000000000000222

Boot HART MEDELEG         : 0x000000000000b109

[    0.000000] OF: fdt: Ignoring memory range 0x80000000 - 0x80200000

[    0.000000] Linux version 5.4.0 (harriszh@pc-harriszh2) (gcc version 10.2.0 (GCC)) #1 SMP Sat Nov 28 13:48:10 CST 2020

[    0.000000] initrd not found or empty - disabling initrd

[    0.000000] Zone ranges:

[    0.000000]   DMA32    [mem 0x0000000080200000-0x000000008fffffff]

[    0.000000]   Normal   empty

[    0.000000] Movable zone start for each node

[    0.000000] Early memory node ranges

[    0.000000]   node   0: [mem 0x0000000080200000-0x000000008fffffff]

[    0.000000] Initmem setup node 0 [mem 0x0000000080200000-0x000000008fffffff]

[    0.000000] software IO TLB: mapped [mem 0x8bc7a000-0x8fc7a000] (64MB)

[    0.000000] elf_hwcap is 0x112d

[    0.000000] percpu: Embedded 17 pages/cpu s30680 r8192 d30760 u69632

[    0.000000] Built 1 zonelists, mobility grouping on.  Total pages: 64135

[    0.000000] Kernel command line: root=/dev/vda rw console=ttyS0

[    0.000000] Dentry cache hash table entries: 32768 (order: 6, 262144 bytes, linear)

[    0.000000] Inode-cache hash table entries: 16384 (order: 5, 131072 bytes, linear)

[    0.000000] Sorting __ex_table...

[    0.000000] mem auto-init: stack:off, heap alloc:off, heap free:off

[    0.000000] Memory: 181052K/260096K available (6167K kernel code, 387K rwdata, 1962K rodata, 213K init, 305K bss, 79044K reserved, 0K cma-reserved)

[    0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=1, Nodes=1

[    0.000000] rcu: Hierarchical RCU implementation.

[    0.000000] rcu:     RCU restricting CPUs from NR_CPUS=8 to nr_cpu_ids=1.

[    0.000000] rcu: RCU calculated value of scheduler-enlistment delay is 25 jiffies.

[    0.000000] rcu: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=1

[    0.000000] NR_IRQS: 0, nr_irqs: 0, preallocated irqs: 0

[    0.000000] plic: mapped 53 interrupts with 1 handlers for 2 contexts.

[    0.000000] riscv_timer_init_dt: Registering clocksource cpuid [0] hartid [0]

[    0.000000] clocksource: riscv_clocksource: mask: 0xffffffffffffffff max_cycles: 0x24e6a1710, max_idle_ns: 440795202120 ns

[    0.000084] sched_clock: 64 bits at 10MHz, resolution 100ns, wraps every 4398046511100ns

[    0.003039] Console: colour dummy device 80x25

[    0.004051] Calibrating delay loop (skipped), value calculated using timer frequency.. 20.00 BogoMIPS (lpj=40000)

[    0.004169] pid_max: default: 32768 minimum: 301

[    0.005060] Mount-cache hash table entries: 512 (order: 0, 4096 bytes, linear)

[    0.005089] Mountpoint-cache hash table entries: 512 (order: 0, 4096 bytes, linear)

[    0.027241] rcu: Hierarchical SRCU implementation.

[    0.028802] smp: Bringing up secondary CPUs ...

[    0.028883] smp: Brought up 1 node, 1 CPU

[    0.036075] devtmpfs: initialized

[    0.040712] random: get_random_u32 called from bucket_table_alloc.isra.0+0x4e/0x154 with crng_init=0

[    0.042384] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 7645041785100000 ns

[    0.042546] futex hash table entries: 256 (order: 2, 16384 bytes, linear)

[    0.045024] NET: Registered protocol family 16

[    0.078034] vgaarb: loaded

[    0.078849] SCSI subsystem initialized

[    0.080125] usbcore: registered new interface driver usbfs

[    0.080352] usbcore: registered new interface driver hub

[    0.080466] usbcore: registered new device driver usb

[    0.086693] clocksource: Switched to clocksource riscv_clocksource

[    0.098120] NET: Registered protocol family 2

[    0.101335] tcp_listen_portaddr_hash hash table entries: 256 (order: 0, 4096 bytes, linear)

[    0.101409] TCP established hash table entries: 2048 (order: 2, 16384 bytes, linear)

[    0.101553] TCP bind hash table entries: 2048 (order: 3, 32768 bytes, linear)

[    0.101679] TCP: Hash tables configured (established 2048 bind 2048)

[    0.102935] UDP hash table entries: 256 (order: 1, 8192 bytes, linear)

[    0.103101] UDP-Lite hash table entries: 256 (order: 1, 8192 bytes, linear)

[    0.104159] NET: Registered protocol family 1

[    0.106058] RPC: Registered named UNIX socket transport module.

[    0.106109] RPC: Registered udp transport module.

[    0.106120] RPC: Registered tcp transport module.

[    0.106130] RPC: Registered tcp NFSv4.1 backchannel transport module.

[    0.106204] PCI: CLS 0 bytes, default 64

[    0.111668] workingset: timestamp_bits=62 max_order=16 bucket_order=0

[    0.120454] NFS: Registering the id_resolver key type

[    0.121100] Key type id_resolver registered

[    0.121132] Key type id_legacy registered

[    0.121218] nfs4filelayout_init: NFSv4 File Layout Driver Registering...

[    0.121748] 9p: Installing v9fs 9p2000 file system support

[    0.122715] NET: Registered protocol family 38

[    0.122915] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 253)

[    0.123007] io scheduler mq-deadline registered

[    0.123065] io scheduler kyber registered

[    0.124868] pci-host-generic 30000000.pci: host bridge /soc/pci@30000000 ranges:

[    0.126286] pci-host-generic 30000000.pci:    IO 0x03000000..0x0300ffff -> 0x00000000

[    0.126630] pci-host-generic 30000000.pci:   MEM 0x40000000..0x7fffffff -> 0x40000000

[    0.128296] pci-host-generic 30000000.pci: ECAM at [mem 0x30000000-0x3fffffff] for [bus 00-ff]

[    0.128985] pci-host-generic 30000000.pci: PCI host bridge to bus 0000:00

[    0.129117] pci_bus 0000:00: root bus resource [bus 00-ff]

[    0.129205] pci_bus 0000:00: root bus resource [io  0x0000-0xffff]

[    0.129218] pci_bus 0000:00: root bus resource [mem 0x40000000-0x7fffffff]

[    0.129911] pci 0000:00:00.0: [1b36:0008] type 00 class 0x060000

[    0.176526] Serial: 8250/16550 driver, 4 ports, IRQ sharing disabled

[    0.181177] printk: console [ttyS0] disabled

[    0.181916] 10000000.uart: ttyS0 at MMIO 0x10000000 (irq = 10, base_baud = 230400) is a 16550A

[    0.194577] printk: console [ttyS0] enabled

[    0.196238] [drm] radeon kernel modesetting enabled.

[    0.208747] loop: module loaded

[    0.218802] virtio_blk virtio0: [vda] 2097152 512-byte logical blocks (1.07 GB/1.00 GiB)

[    0.237502] libphy: Fixed MDIO Bus: probed

[    0.238225] e1000e: Intel(R) PRO/1000 Network Driver - 3.2.6-k

[    0.238402] e1000e: Copyright(c) 1999 - 2015 Intel Corporation.

[    0.238741] ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver

[    0.238903] ehci-pci: EHCI PCI platform driver

[    0.239112] ehci-platform: EHCI generic platform driver

[    0.239558] ohci_hcd: USB 1.1 'Open' Host Controller (OHCI) Driver

[    0.239747] ohci-pci: OHCI PCI platform driver

[    0.239967] ohci-platform: OHCI generic platform driver

[    0.240461] usbcore: registered new interface driver uas

[    0.240688] usbcore: registered new interface driver usb-storage

[    0.241550] mousedev: PS/2 mouse device common for all mice

[    0.242575] usbcore: registered new interface driver usbhid

[    0.242704] usbhid: USB HID core driver

[    0.244104] NET: Registered protocol family 10

[    0.248951] Segment Routing with IPv6

[    0.250166] sit: IPv6, IPv4 and MPLS over IPv4 tunneling driver

[    0.253011] NET: Registered protocol family 17

[    0.254283] 9pnet: Installing 9P2000 support

[    0.254605] Key type dns_resolver registered

[    0.289007] EXT4-fs (vda): mounted filesystem with ordered data mode. Opts: (null)

[    0.289554] VFS: Mounted root (ext4 filesystem) on device 254:0.

[    0.292116] devtmpfs: mounted

[    0.309109] Freeing unused kernel memory: 212K

[    0.309271] This architecture does not have kernel memory protection.

[    0.309452] Run /sbin/init as init process

Please press Enter to activate this console. 

/ # ls

bin         etc         lost+found  sbin        usr

dev         linuxrc     proc        sys

如果要退出系统，输入poweroff

/ # poweroff

/ # umount: devtmpfs busy - remounted read-only

[  112.461233] EXT4-fs (vda): re-mounted. Opts: (null)

swapoff: can't open '/etc/fstab': No such file or directory

The system is going down NOW!

Sent SIGTERM to all processes

Sent SIGKILL to all processes

Requesting system poweroff

[  114.487435] reboot: Power down