About
The riscv_hwprobe syscall (0) allows userspace to probe hardware characteristics in a standardized manner. At this moment the syscall supports probe for:
- mvendorid/marchid/mimpid
- user visible behavior (rv32ima/rv64ima)
- enabled extensions (some, more is being added)
- hart performance information
Linux-user support for riscv_hwprobe will allow RISC-V binaries to fetch system/CPU capabilities on the fly instead of making assumptions inside the code.
(0) https://docs.kernel.org/riscv/hwprobe.html
Project Scope and Timelines
Initial addition to qemu linux-user waiting for kernel release.
Continued tracking kernel capabilities of known extensions is also needed, but not part of this task.
Components and Repos
Main repo: https://gitlab.com/qemu-project/qemu.git
Pending patch: https://lists.gnu.org/archive/html/qemu-devel/2023-06/msg03347.html
As more extensions are being to kernel we need to keep adding them to linux-user (again done outside of this task).
Currently: https://github.com/torvalds/linux/blob/master/arch/riscv/include/uapi/asm/hwprobe.h
Stakeholders and Partners
Other hw/riscv/virt.c contributors
Dependencies
Inclusion in a released kernel (included in 6.4, released 2023-06-25).
Qemu do not include syscalls not yet released.
Measure of Success
Patch integrated.
RISE Requirements
A program should not be able to determine if it's running in qemu linux-user or on bare metal by using riscv_hwprobe syscall.