[PATCH 0/6] target/riscv: Expose RV32 cpu to RV64 QEMU

[LIU Zhiwei]

From: TANG Tiancheng <tangtiancheng.ttc@alibaba-inc.com>

This patch set aims to expose 32-bit RISC-V cpu to RV64 QEMU. Thus
qemu-system-riscv64 can directly boot a RV32 Linux.

This patch set has been tested with 6.9.0 Linux Image.

- Run RV64 QEMU with RV32 CPU
qemu-system-riscv64 -cpu rv32 -M virt -nographic \
    -kernel Image \
    -append "root=/dev/vda ro console=ttyS0" \
    -drive file=rootfs.ext2,format=raw,id=hd0 \
    -device virtio-blk-device,drive=hd0 -netdev user,id=net0 \
    -device virtio-net-device,netdev=net0

OpenSBI v1.4
QEMU emulator version 9.0.50 (v9.0.0-1132-g7799dc2e3b)
[    0.000000] Linux version 6.9.0 (developer@11109ca35736) 
(riscv32-unknown-linux-gnu-gcc (gc891d8dc23e-dirty) 13.2.0, GNU ld (GNU 
Binutils) 2.42) #3 SMP Fri May 31 08:42:15 UTC 2024
[    0.000000] random: crng init done
[    0.000000] OF: fdt: Ignoring memory range 0x80000000 - 0x80400000
[    0.000000] Machine model: riscv-virtio,qemu
[    0.000000] SBI specification v2.0 detected
[    0.000000] SBI implementation ID=0x1 Version=0x10004
[    0.000000] SBI TIME extension detected
[    0.000000] SBI IPI extension detected
[    0.000000] SBI RFENCE extension detected
[    0.000000] SBI SRST extension detected
[    0.000000] SBI DBCN extension detected
[    0.000000] efi: UEFI not found.
[    0.000000] OF: reserved mem: 0x80000000..0x8003ffff (256 KiB) nomap 
non-reusable mmode_resv1@80000000
[    0.000000] OF: reserved mem: 0x80040000..0x8004ffff (64 KiB) nomap 
non-reusable mmode_resv0@80040000
[    0.000000] Zone ranges:
[    0.000000]   Normal   [mem 0x0000000080400000-0x0000000087ffffff]
[    0.000000] Movable zone start for each node
[    0.000000] Early memory node ranges
[    0.000000]   node   0: [mem 0x0000000080400000-0x0000000087ffffff]
[    0.000000] Initmem setup node 0 [mem 0x0000000080400000-0x0000000087ffffff]
[    0.000000] On node 0, zone Normal: 1024 pages in unavailable ranges
[    0.000000] SBI HSM extension detected
[    0.000000] riscv: base ISA extensions acdfhim
[    0.000000] riscv: ELF capabilities acdfim
[    0.000000] percpu: Embedded 17 pages/cpu s37728 r8192 d23712 u69632
[    0.000000] Kernel command line: root=/dev/vda ro console=ttyS0
[    0.000000] Dentry cache hash table entries: 16384 (order: 4, 65536 bytes, 
linear)
[    0.000000] Inode-cache hash table entries: 8192 (order: 3, 32768 bytes, 
linear)
[    0.000000] Built 1 zonelists, mobility grouping on.  Total pages: 31465
[    0.000000] mem auto-init: stack:all(zero), heap alloc:off, heap free:off
[    0.000000] Virtual kernel memory layout:
[    0.000000]       fixmap : 0x9c800000 - 0x9d000000   (8192 kB)
[    0.000000]       pci io : 0x9d000000 - 0x9e000000   (  16 MB)
[    0.000000]      vmemmap : 0x9e000000 - 0xa0000000   (  32 MB)
[    0.000000]      vmalloc : 0xa0000000 - 0xc0000000   ( 512 MB)
[    0.000000]       lowmem : 0xc0000000 - 0xc7c00000   ( 124 MB)
[    0.000000] Memory: 95700K/126976K available (9090K kernel code, 8845K 
rwdata, 4096K rodata, 4231K init, 341K bss, 31276K reserved, 0K cma-reserved)
...
Welcome to Buildroot
buildroot login: root
# cat /proc/cpuinfo
processor       : 0
hart            : 0
isa             : 
rv32imafdch_zicbom_zicboz_zicntr_zicsr_zifencei_zihintntl_zihintpause_zihpm_zfa_zba_zbb_zbc_zbs_sstc
mmu             : sv32

TANG Tiancheng (6):
  target/riscv: Add fw_dynamic_info32 for booting RV32 OpenSBI
  target/riscv: Adjust PMP size for no-MMU RV64 QEMU running RV32
  target/riscv: Correct SXL return value for RV32 in RV64 QEMU
  target/riscv: Detect sxl to set bit width for RV32 in RV64
  target/riscv: Correct mcause/scause bit width for RV32 in RV64 QEMU
  target/riscv: Enable RV32 CPU support in RV64 QEMU

 configs/targets/riscv64-softmmu.mak |  2 +-
 hw/riscv/boot.c                     | 35 +++++++++++++++++++----------
 hw/riscv/sifive_u.c                 |  3 ++-
 include/hw/riscv/boot.h             |  4 +++-
 include/hw/riscv/boot_opensbi.h     | 29 ++++++++++++++++++++++++
 target/riscv/cpu.c                  | 17 ++++++++++----
 target/riscv/cpu.h                  |  5 ++++-
 target/riscv/cpu_helper.c           | 23 ++++++++++++++-----
 target/riscv/pmp.c                  |  2 +-
 9 files changed, 93 insertions(+), 27 deletions(-)

-- 
2.43.0