cyyself/cemu

A simple full system emulator. Currently support RV64IMACSU and MIPS32 and LoongArch32. Capable of booting Linux. Suitable for education and research.

cemu's Issues

How can I attach the rootfs image to the emulator?

Hi there! I really appreciate your time and your reply. As you could see, I am a beginner of RISC-V and Linux, so please forgive me if I am asking silly questions.

For the last few days, I managed to build a usable opensbi binary (without payload) for cemu (at least it prints and did not panic) and a Linux kernel (version 5.2.11).

I followed the instruction you mentioned and referred to some other threads, and successfully built an opensbi with linux kernel as payload. However, when I load the new opensbi with linux kernel, the cemu emulator prints nothing after the opensbi info.

Since the process of building the kernel did not use the dtc file, I think there must exists some mechanism that passes the dtb to the kernel. After some STFW, I found that the address dtb struct should be passed via r2 register, but maybe for some reason, it does not success.

To make sure if the kernel works, I tried to run the kernel with qemu-system-riscv64. For now, although I did not provide a rootfs, I believe the kernel should at least print some logs. I tried to run the kernel with command qemu-system-riscv64 -machine virt -nographic -kernel ../linux/arch/riscv/boot/Image -append "root=/dev/vda ro console=ttyS0" -m 128, what I got are just some opensbi logs, it seems that the kernel have another opensbi built-in.

So my question is:

• How to provide the rootfs to CEMU? AFAIK, we need an additional block device to do so.
• Is it necessary to provide the dtc when compiling Linux kernel?

Here are my logs FYI:

Trying to load kernel directly with QEMU:

❯ qemu-system-riscv64 -machine virt -nographic -kernel ../linux/arch/riscv/boot/Image -append "root=/dev/vda ro console=ttyS0" -m 128

OpenSBI v1.0
   ____                    _____ ____ _____
  / __ \                  / ____|  _ \_   _|
 | |  | |_ __   ___ _ __ | (___ | |_) || |
 | |  | | '_ \ / _ \ '_ \ \___ \|  _ < | |
 | |__| | |_) |  __/ | | |____) | |_) || |_
  \____/| .__/ \___|_| |_|_____/|____/_____|
        | |
        |_|

Platform Name             : riscv-virtio,qemu
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    : sifive_test
Platform Shutdown Device  : sifive_test
Firmware Base             : 0x80000000
Firmware Size             : 252 KB
Runtime SBI Version       : 0.3

Domain0 Name              : root
Domain0 Boot HART         : 0
Domain0 HARTs             : 0*
Domain0 Region00          : 0x0000000002000000-0x000000000200ffff (I)
Domain0 Region01          : 0x0000000080000000-0x000000008003ffff ()
Domain0 Region02          : 0x0000000000000000-0xffffffffffffffff (R,W,X)
Domain0 Next Address      : 0x0000000080200000
Domain0 Next Arg1         : 0x0000000087000000
Domain0 Next Mode         : S-mode
Domain0 SysReset          : yes

Boot HART ID              : 0
Boot HART Domain          : root
Boot HART ISA             : rv64imafdcsuh
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 MIDELEG         : 0x0000000000001666
Boot HART MEDELEG         : 0x0000000000f0b509

Run the opensbi binary with kernel as payload in CEMU:

OpenSBI v1.3-49-gee1f83c
   ____                    _____ ____ _____
  / __ \                  / ____|  _ \_   _|
 | |  | |_ __   ___ _ __ | (___ | |_) || |
 | |  | | '_ \ / _ \ '_ \ \___ \|  _ < | |
 | |__| | |_) |  __/ | | |____) | |_) || |_
  \____/| .__/ \___|_| |_|_____/|____/_____|
        | |
        |_|

Platform Name             : cyy,cemu
Platform Features         : medeleg
Platform HART Count       : 2
Platform IPI Device       : aclint-mswi
Platform Timer Device     : aclint-mtimer @ 100000000Hz
Platform Console Device   : xlnx-uartlite
Platform HSM Device       : ---
Platform PMU Device       : ---
Platform Reboot Device    : ---
Platform Shutdown Device  : ---
Platform Suspend Device   : ---
Platform CPPC Device      : ---
Firmware Base             : 0x80000000
Firmware Size             : 332 KB
Firmware RW Offset        : 0x40000
Firmware RW Size          : 76 KB
Firmware Heap Offset      : 0x4a000
Firmware Heap Size        : 36 KB (total), 2 KB (reserved), 9 KB (used), 24 KB (free)
Firmware Scratch Size     : 4096 B (total), 768 B (used), 3328 B (free)
Runtime SBI Version       : 1.0

Domain0 Name              : root
Domain0 Boot HART         : 0
Domain0 HARTs             : 0*,1*
Domain0 Region00          : 0x0000000002000000-0x000000000200ffff M: (I,R,W) S/U: ()
Domain0 Region01          : 0x0000000080040000-0x000000008005ffff M: (R,W) S/U: ()
Domain0 Region02          : 0x0000000080000000-0x000000008003ffff M: (R,X) S/U: ()
Domain0 Region03          : 0x0000000000000000-0xffffffffffffffff M: () S/U: (R,W,X)
Domain0 Next Address      : 0x0000000080200000
Domain0 Next Arg1         : 0x0000000082200000
Domain0 Next Mode         : S-mode
Domain0 SysReset          : yes
Domain0 SysSuspend        : yes

Boot HART ID              : 0
Boot HART Domain          : root
Boot HART Priv Version    : v1.10
Boot HART Base ISA        : rv64imac
Boot HART ISA Extensions  : none
Boot HART PMP Count       : 0
Boot HART PMP Granularity : 0
Boot HART PMP Address Bits: 0
Boot HART MHPM Info       : 0 (0x00000000)
Boot HART MIDELEG         : 0x0000000000000222
Boot HART MEDELEG         : 0x000000000000b109

Solution to extension `zicsr' required error when compiling

The zicsr instruction set was made separate as an extension. We have to build opensbi with PLATFORM_RISCV_ISA=rv64ima_zicsr_zifencei.

For older linux kernel version, refer to this solution.

How to use CEMU for difftest?

Maybe information about difftest is missing from the repo quoted at:

cemu/README.md

Line 5 in e90f95e

Easy to be used for difftest with [soc-simulator](https://github.com/cyyself/soc-simulator).

Would you please show a demo for "How to use CEMU for difftest"?