RVVM - HackMD

--- tags: Computer Architecture --- # RVVM contributed by <`huang-me`>, <`OliveLake`> :::info Expectation - [x] RVVM ( https://github.com/LekKit/RVVM ) 同時支援 RV64 和 RV32，本課程著重於 RV32，請針對 RV32 準備相關的開發工具 (可重用 GNU Toolchain) - [x] 留意 Linux 啟動流程: OpenSBI -> U-Boot -> Linux kernel -> userspace，請學習相關的背景知識，說明個別元件的作用，特別是 OpenSBI - [ ] 準備 RV32 的 Linux 核心，你們可能會遭遇技術困難，記錄下來並嘗試排除 - [ ] 說明 Linux 核心在 RV32/RVVM 啟動過程中，除了 CPU，還有哪些週邊的互動 (如中斷控制器和 timer) - [ ] RVVM 可通過 RISC-V compliance tests，請以最新的程式碼搭配新的測試，確認在 RV32 (及相關 extension) 得以通過，並記錄過程，若發現問題就回報給 RVVM 開發團隊. ::: ## Introduction As shown in figure below ![](https://i.imgur.com/vfYeMHM.png) RVVM replace QEMU, and we need to prepare `OS kernel` & `cross compiler tools` & ==Distributions== for it. ## Prerequisites to build RVVM ### Build riscv32 linux toolchain There are two types riscv-gnu-toolchain, 1. `riscv32-unknown-elf-gcc`, cross compiler using newlib for 32bit RISC-V bare-metal. 2. `riscv32-unknown-linux-gnu-gcc`, corss compiler using glibc which provides the core libraries for GNU/Linux systems. :::spoiler stupid try ## Why wrong **Toolchain leading with `riscv-none-embed-` is toolchain for ==embedded system==. We're going to build risc-v linux, so we need toolchain leading with `riscv64-unknown-linux-gnu-`.** ### Build OpenSBI ```shell= export CROSS_COMPILE=riscv-none-embed- git clone https://github.com/starfive-tech/opensbi.git cd opensbi make PLATFORM="generic" ``` - `fw_jump.bin` will be generated in `opensbi/build/platform/generic/firmware` ### Build linux kernel ```shell= // generate config make ARCH=riscv CROSS_COMPILE=riscv-none-embed- defconfig // compile make ARCH=riscv CROSS_COMPILE=riscv-none-embed- -j 4 ``` - `Image` will be generated in `linux/arch/riscv/boot` ### Build busy box ```shell= git clone https://git.busybox.net/busybox cd busybox CROSS_COMPILE=riscv-none-embed- make menuconfig CROSS_COMPILE=riscv-none-embed- make // error ``` :::danger ``` include/platform.h:168:11: fatal error: byteswap.h: No such file or directory 168 | # include <byteswap.h> | ^~~~~~~~~~~~ ``` riscv-none-embed- has no `byteswap.h` ::: #### Prerequisite For ubuntu, there are some needed packages to build toolchain. ``` $ sudo apt-get install autoconf automake autotools-dev curl python3 libmpc-dev libmpfr-dev libgmp-dev gawk build-essential bison flex texinfo gperf libtool patchutils bc zlib1g-dev libexpat-dev ``` #### Installation ```shell git clone https://github.com/riscv-collab/riscv-gnu-toolchain.git --recursive cd riscv-gnu-toolchain ./configure --prefix=/opt/riscv32-linux --with-arch=rv32imc --enable-linux sudo make linux ``` #### Errors in building riscv linux toolchain After `sudo make linux` ``` error : mips nios2 powerpc riscv glibc requires the A extension ``` Because RISC-V Linux require `A-extension` as minimal requirement, so at least we should use `--wtih-arch=rv32ia` or `--with-arch=rv64ia` for building linux toolchain. We sholud use ``` make clean ./configure --prefix=opt/riscv32-linux --with-arch=rv32imac --enable-linux make linux ``` ==PICTURE== ### Setup toolchain & environment variable ```shell export PATH=$PATH:/opt/riscv32-linux/bin export CROSS_COMPILE=riscv32-unknown-linux-gnu- export ARCH=riscv ``` ## Introduction for Boot flow ### RISC-V Upstream Boot Flow ![](https://i.imgur.com/nsmnLPU.png) * ZSBL(Zeroth Stage Boot Loader): Initial platform-specific bootloader,the first program being run after power-on. Core starts fetching from ROM of SoC, copying FSBL image from SD into memory. * FSBL(first Stage Boot Loader): Initial platform-specific bootloader. FSBL is SiFive specific and will be replaced by Coreboot/U-Boot SPL. :::spoiler What is U-Boot SPL Usually regular bootloader (e.g. U-Boot) binary is bigger than SRAM, So we need to create some additional bootloader, referred as first-stage bootloader (in two-stage bootloader scenario). Regularly the first-stage bootloader is U-Boot SPL, and the second-stage bootloader is U-Boot. ::: <br> * OpenSBI: The RISC-V Supervisor Binary Interface (SBI) specifications. Aimed at providing RUNTIME services in M-mode, typically used in boot stage following ROM/LOADER. :::warning RVVM allows boot the Linux kernel directly after SBI, without U-Boot. Therefore we need to execute `fw_jump.bin` which contain OpenSBI and initial firmware. ::: * fw_jump: Firmware provides by OpenSBI with `static` jump address to the next booting stage, so previous booting stage (i.e. LOADER) has to load next booting stage (i.e. BOOTLADER) at a fixed location. ![](https://i.imgur.com/oSJdqPZ.png) ### Build linux kernel image Create simple Hello world of booting Linux on RVVM ``` mkdir riscv32-linux cd riscv32-linux git clone https://github.com/torvalds/linux git checkout v5.4.0 make ARCH=riscv CROSS_COMPILE=riscv32-unknown-linux-gnu- defconfig ``` ### Build U-Boot ```shell= git clone https://github.com/u-boot/u-boot.git make qemu-riscv32_smode_defconfig make ``` ### Build OpenSBI ```shell git clone https://github.com/starfive-tech/opensbi.git cd opensbi make PLATFORM="generic" FW_PAYLOAD_PATH=../u-boot/u-boot.bin ``` error occurs ``` cc: error: unrecognized argument in option ‘-mabi=lp64’ cc: note: valid arguments to ‘-mabi=’ are: ms sysv cc: error: unrecognized argument in option ‘-mcmodel=medany’ cc: note: valid arguments to ‘-mcmodel=’ are: 32 kernel large medium small; did you mean ‘medium’? ``` Caused by failing to use RISC-V compiler, reset path: ``` export CROSS_COMPILE=/opt/riscv32-unknown-linux-gnu- ``` `fw_jump.bin` will be generated in `opensbi/build/platform/generic/firmware` ## Build RVVM Build RVVM using GNU make on linux ``` git clone https://github.com/LekKit/RVVM cd RVVM make ``` There is an error about `no such file or directory : X11/keysym.h & X11/extentions/XShm.h` Solution : ``` sudo apt install libx11-dev sudo apt install x11proto-xext-dev ``` Then keep building RVVM ``` cd release.linux.riscv ./rvvm_riscv fw_jump.bin -kernel linux_Imag -mem 2G -smp 2 -res 1280x720 ``` :::danger loop forever ![](https://i.imgur.com/ElAPOgC.png) ::: After contact with RVVM team, it seems like we are running U-Boot as SBI payload, and U-Boot tries to access MMC flash - RVVM doesn't support flash (yet), so U-Boot keep resets the VM. One solution is we built U-Boot with IDE (ATA) hard-drives, and another way is we boot the Linux kernel directly after SBI, without U-Boot. ==Rebuild without U-Boot== ``` make PLATFORM="generic" ``` ``` cd release.linux.riscv ./rvvm_riscv fw_jump.bin -kernel linux_Imag ``` ![](https://i.imgur.com/OAH1mMf.png) ### Build Distributions There is not that much pre-built distributions for 32-bit RISC-V, so we use `Buildroot` ``` ./rvvm_riscv fw_jump.bin -kernel linux_image -image rootfs.img -mem 1G -res 1280x720 ``` ![](https://i.imgur.com/9f9Iux7.png) ### Complience Test #### What complience test for? Due to RISC-V is an open ISA, and the freedom of extending the ISA with custom instructions and extensions, the compliance tests are essential to confirm the basic operation is in accordance with the specification #### Start Test TODO ![](https://i.imgur.com/VcVDGty.png)

Syntax	Example	Reference
# Header	Header	基本排版
- Unordered List	Unordered List
1. Ordered List	Ordered List
- [ ] Todo List	Todo List
> Blockquote	Blockquote
Bold font	Bold font
Italics font	Italics font
~~Strikethrough~~	~~Strikethrough~~
19^th^	19^th
H~2~O	H₂O
++Inserted text++	Inserted text
==Marked text==	Marked text
[link text](https:// "title")	Link
![image alt](https:// "title")	Image
`Code`	`Code`	在筆記中貼入程式碼
```javascript var i = 0; ```	`var i = 0;`
:smile:		Emoji list
{%youtube youtube_id %}	Externals
$L^aT_eX$	L^aT_eX
:::info This is a alert area. :::	This is a alert area.