rv32-emu

• This is a learning purpose project for myself and it is porting from sysprog21/semu. rv32-emu is a 32bits version of semu and currently supports basic RV32GC and it can boot the xv6-rv32 kernel. It might be incomplete and have bugs, if somebody want to discussion about that, welcome to contact me :).
• These are my reference project and study resources.
  • RinHizakura/riscv-emulator
  • sysprog21/rv32emu
  • sysprog21/semu
  • franzflasch/riscv_em
• Support features
  • [DONE] RV32G
  • [WIP ] RV32C
  • [WIP ] RV32F
  • [DONE] Privilege levels
  • [DONE] CSR
  • [DONE] Sv32
  • [DONE] UART
  • [DONE] CLINT
  • [DONE] PLIC
  • [DONE] VIRTIO
• Support Kernel
  • [WIP ] xv6-rv32 (some bug for current commit)
  • [WIP ] Linux kernel v5.4

Build

• Build the rv32-emu:

  $ make

• Build riscv32 toolchain:

  • Without Float/Double.

    $ git clone https://github.com/riscv-collab/riscv-gnu-toolchain.git
    $ cd riscv-gnu-toolchain
    $ ./configure --prefix=/opt/riscv --with-arch=rv32imac --with-abi=ilp32
    $ sudo make -j4

• Build the u-boot:

  
  $ git clone https://github.com/u-boot/u-boot.git
  $ export CROSS_COMPILE=/<pathto>/riscv32-unknown-linux-gnu-
  $ make

* Build the Opensbi:
```shell
$ git clone https://github.com/starfive-tech/opensbi.git
$ cd opensbi
$ export CROSS_COMPILE=/<pathto>/riscv32-unknown-linux-gnu-
$ make PLATFORM="generic" FW_PAYLOAD_PATH=../u-boot/u-boot.bin

• Build the Linux Kernel(v5.4)

  
  $ git clone https://github.com/torvalds/linux
  $ cd linux
  $ git checkout v5.4
  $ make ARCH=riscv CROSS_COMPILE=/<pathto>/riscv32-unknown-linux-gnu- rv32_defconfig
  $ vim .config
  ...
  CONFIG_FPU=n
  ...

$ make ARCH=riscv CROSS_COMPILE=//riscv32-unknown-linux-gnu- -j4

$ ls arch/riscv/boot/Image

### Run xv6-rv32

* Output (a little bit slow):
```shell
$ ./rv_emu --elf xv6-rv32/kernel --rootfs xv6-rv32/fs.img

xv6 kernel is booting

init: starting sh
$

Run Opensbi with U-boot

• Output

  
  $ ./rv_emu --bios fw_payload.bin

OpenSBI VF_SDK_510_V1.2.1

Platform Name : rv32-emu Platform Features : medeleg Platform HART Count : 1 Platform IPI Device : aclint-mswi Platform Timer Device : aclint-mtimer @ 10000000Hz Platform Console Device : uart8250 Platform HSM Device : --- Platform Reboot Device : --- Platform Shutdown Device : --- Firmware Base : 0x80000000 Firmware Size : 204 KB Runtime SBI Version : 0.3

Domain0 Name : root Domain0 Boot HART : 0 Domain0 HARTs : 0* Domain0 Region00 : 0x02000000-0x0200ffff (I) Domain0 Region01 : 0x80000000-0x8003ffff () Domain0 Region02 : 0x00000000-0xffffffff (R,W,X) Domain0 Next Address : 0x80400000 Domain0 Next Arg1 : 0x82200000 Domain0 Next Mode : S-mode Domain0 SysReset : yes

Boot HART ID : 0 Boot HART Domain : root Boot HART ISA : rv32imacsu Boot HART Features : scounteren,mcounteren,mcountinhibit,sscofpmf,time Boot HART PMP Count : 64 Boot HART PMP Granularity : 4 Boot HART PMP Address Bits: 32 Boot HART MHPM Count : 29 Boot HART MIDELEG : 0x00002222 Boot HART MEDELEG : 0x0000b109

U-Boot 2022.10-rc3-00062-g4e10c1227a-dirty (Sep 05 2022 - 00:46:20 +0800)

CPU: rv32imacsu Model: rv32-emu DRAM: 128 MiB Core: 13 devices, 9 uclasses, devicetree: board Loading Environment from nowhere... OK In: uart@10000000 Out: uart@10000000 Err: uart@10000000 Net: No ethernet found. Hit any key to stop autoboot: 1 0 => bdinfo

......

### Run Linux with OpenSBI

* Reference Output
    * FIXME: UART has bugs.
```shell
$ ./rv_emu --bios fw_jump.bin --kernel Image --rootfs busybox.bin --dtb dts/riscv_em.dtb

[    3.433362] virtio_blk virtio0: [vda] 65536 512-byte logical blocks (33.6 MB/32.0 MiB)
[    3.477636] libphy: Fixed MDIO Bus: probed
[    3.503936] e1000e: Intel(R) PRO/1000 Network Driver - 3.2.6-k
[    3.505020] e1000e: Copyright(c) 1999 - 2015 Intel Corporation.
[    3.509911] ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver
[    3.511084] ehci-pci: EHCI PCI platform driver
[    3.513450] ehci-platform: EHCI generic platform driver
[    3.516399] ohci_hcd: USB 1.1 'Open' Host Controller (OHCI) Driver
[    3.517527] ohci-pci: OHCI PCI platform driver
[    3.519893] ohci-platform: OHCI generic platform driver
[    3.528264] usbcore: registered new interface driver uas
[    3.531347] usbcore: registered new interface driver usb-storage
[    3.536688] mousedev: PS/2 mouse device common for all mice
[    3.547580] usbcore: registered new interface driver usbhid
[    3.548594] usbhid: USB HID core driver
[    3.589643] NET: Registered protocol family 10
[    3.614942] Segment Routing with IPv6
[    3.618890] sit: IPv6, IPv4 and MPLS over IPv4 tunneling driver
[    3.643992] NET: Registered protocol family 17
[    3.654559] 9pnet: Installing 9P2000 support
[    3.656964] Key type dns_resolver registered
[    3.691009] EXT4-fs (vda): mounting ext2 file system using the ext4 subsystem
[    3.741424] EXT4-fs (vda): warning: mounting unchecked fs, running e2fsck is recommended
[    3.755032] EXT4-fs (vda): mounted filesystem without journal. Opts: (null)
[    3.757121] VFS: Mounted root (ext2 filesystem) on device 254:0.
[    3.761763] devtmpfs: mounted
[    3.769553] Freeing unused kernel memory: 192K
[    3.770454] This architecture does not have kernel memory protection.
[    3.771604] Run /sbin/init as init process
can't run '/etc 

Compliance Test

• Passed Tests

  • I : Base Integer Instruction Set
  • M : Standard Extension for Integer Multiplication and Division

• Failed Tests

  • C : Standard Extension for Compressed Instruction
    • c.ebreak

• Build and test:

  
  $ make clean

$ make CONFIG_ARCH_TEST=1 arch-test RISCV_DEVICE=I $ make CONFIG_ARCH_TEST=1 arch-test RISCV_DEVICE=M $ make CONFIG_ARCH_TEST=1 arch-test RISCV_DEVICE=C