lssbi

lssbi lists information about the active RISC-V SBI environment.

The current backend reads values exported by the lssbi_probe DKMS module. The command itself is unprivileged and never loads or unloads kernel modules.

Demo

Build

git clone https://github.com/rustsbi/lssbi.git
cd lssbi
cargo build
cargo run

Building the command does not require kernel headers. The gettext catalogs are compiled into target/<profile>/locale.

Install the command

sudo ./install.sh

The defaults are PREFIX=/usr/local and PROFILE=debug; packagers may also set DESTDIR. The executable is installed as a normal mode-0755 program in $PREFIX/bin.

For a release build:

cargo build --release
sudo PROFILE=release ./install.sh

Install the DKMS backend

Install DKMS and the headers for the running kernel, then run:

sudo dkms add .
sudo dkms build lssbi/0.0.1
sudo dkms install lssbi/0.0.1
sudo modprobe lssbi_probe

To load the module automatically at boot, install the supplied modules-load configuration:

sudo install -Dm644 modules-load.d/lssbi.conf \
    /etc/modules-load.d/lssbi.conf

DKMS builds lssbi_probe.ko for the running kernel and rebuilds it after kernel upgrades. Distribution packages should install the module source and dkms.conf under /usr/src/lssbi-0.0.1/; a Debian package would normally split the project into lssbi and lssbi-dkms binary packages.

Usage

lssbi
lssbi --cpu 3
lssbi --json
lssbi --legacy
lssbi --help
lssbi --version

Example output:

SBI specification: v2.0 (raw 0x2000000)
SBI implementation: OpenSBI (ID 0x1)
SBI implementation version: v1.6 (raw 0x10006)
Machine vendor ID: SpacemiT (Hangzhou)Technology Co Ltd (raw 0x710)
Machine architecture ID: 0x8000000058000002
Machine implementation ID: 0x33d8a600
SBI extensions:
  Base:                           Supported
  Timer:                          Supported
  Inter-processor Interrupt:      Supported
  Remote Fence:                   Supported
  Hart State Management:          Supported
  System Reset:                   Supported
  Performance Monitoring Unit:    Supported
  Debug Console:                  Supported
  System Suspend:                 Supported
  Collab. Processor Perf. Control: Not supported
  Nested Acceleration:            Not supported
  Steal-time Accounting:          Not supported
  Supervisor Software Events:     Supported
  Firmware Features:              Supported
  Debug Triggers:                 Supported
  Message Proxy:                  Supported
Vulnerabilities:
  PMU2 Crash (CVE-2025-63913):    Affected
Firmware Features (Linux CPU #0, SBI hart #0):
  Misaligned Exception Delegation: Not supported
  Landing Pad:                    Not supported
  Shadow Stack:                   Not supported
  Double Trap:                    Not supported
  PTE A/D Hardware Updating:      Not supported
  Pointer Masking PMLEN:          Not supported

--legacy appends probes for the nine deprecated SBI v0.1 calls.

--json emits JSON schema version 1. Its field names and extension/feature keys are stable English identifiers and never follow the user's locale. XLEN-sized raw values, SBI hart IDs, and probe values are lowercase 0x-prefixed hexadecimal strings so 64-bit values remain exact in every JSON implementation. Probe error fields remain signed JSON numbers. For example, a probe result is encoded as {"error":-4,"value":"0x2"}. The schema has these top-level fields:

• schema_version
• sbi_specification
• sbi_implementation
• machine
• extensions
• vulnerabilities
• firmware_features

--json can be combined with --cpu N and --legacy.

--cpu N pins the live per-hart FWFT query to Linux CPU N. Without it, the output identifies whichever CPU serviced the parameter read. Malformed or unavailable values identify the rejected CPU and explain whether it is outside the supported range, offline, or restricted by affinity/cpuset.

If the module is not loaded, lssbi reports the unavailable DKMS backend and suggests sudo modprobe lssbi_probe.

Output follows the invoking user's locale. Use LC_ALL=C lssbi to force English.

Translation

Gettext sources follow the conventional po/ layout: LINGUAS lists locales, POTFILES.in lists translatable sources, and <locale>.po contains each translation. Cargo compiles them into target/<profile>/locale.

The ar, es, fr, ru, zh_CN, and zh_TW catalogs cover every displayed Base field, extension, vulnerability, FWFT feature, status, and backend error. Generic language catalogs such as fr are also used by regional locales through gettext fallback.

Requirements

• riscv64 Linux booted through SBI
• Rust and Cargo for building the command
• DKMS, GNU Make, and matching kernel headers for building lssbi_probe
• Kernel module support and a policy that permits the module to be loaded

Design

The GPL-2.0-only lssbi_probe module reads the immutable SBI Base and machine identity fields when it is loaded. It caches them in read-only module parameters under:

/sys/module/lssbi_probe/parameters/spec_version
/sys/module/lssbi_probe/parameters/impl_id
/sys/module/lssbi_probe/parameters/impl_version
/sys/module/lssbi_probe/parameters/mvendorid
/sys/module/lssbi_probe/parameters/marchid
/sys/module/lssbi_probe/parameters/mimpid

It also probes the 16 current extensions and nine optional legacy calls once at load time. Their SBI error/value pairs are exposed together under:

/sys/module/lssbi_probe/parameters/extensions

FWFT state is intentionally not cached. Reading this additional parameter invokes a getter that executes FWFT GET for all six standard features:

/sys/module/lssbi_probe/parameters/fwft

One read returns a single live sample in the following stable format:

cpu <linux-cpu-id>
hart <sbi-hart-id>
misaligned_exc_deleg <sbi-error> <value>
landing_pad <sbi-error> <value>
shadow_stack <sbi-error> <value>
double_trap <sbi-error> <value>
pte_ad_hw_updating <sbi-error> <value>
pointer_masking_pmlen <sbi-error> <value>

The getter prevents CPU migration while making the six calls because these standard FWFT features are local to a hart and may change at runtime. It reports both the Linux CPU ID and the kernel's corresponding SBI hart ID. --cpu N narrows the command's CPU affinity before reading the parameter; without it, the scheduler selects the sampled CPU. lssbi reads the parameter once each time it runs and preserves each call's SBI error separately from its value. The CLI converts those raw results into localized status text instead of exposing an unexplained SBI error or hexadecimal zero.

SBI does not define hardware discovery, so lssbi does not try to enumerate CPUs from SBI data.

The six GET calls are consecutive but not an atomic firmware transaction; FWFT defines only a single-feature GET operation.

The module has no writable parameters, device node, ioctl interface, dynamic allocation, or background activity. It stays loaded so any user can run lssbi without setuid, PAM, or CAP_SYS_MODULE.

The module's private SBI call primitive accepts an extension ID, function ID, and six arguments. It is shared by the cached Base queries and the live FWFT getter.

The backend boundary is kept separate from presentation. A future native Linux sysfs backend can be preferred automatically while retaining the DKMS backend as a compatibility fallback.

Development notes

Refresh the DKMS module

DKMS caches builds by module version. When kernel module output changes without a version bump, rebuilding the existing lssbi/0.0.1 entry may keep the old module. Remove that development entry before rebuilding it:

sudo modprobe -r lssbi_probe
sudo dkms remove lssbi/0.0.1 --all
sudo dkms add .
sudo dkms build lssbi/0.0.1
sudo dkms install lssbi/0.0.1
sudo modprobe lssbi_probe

After a version bump, replace 0.0.1 with the version in dkms.conf. Confirm that the live FWFT parameter uses the current record format before testing the command:

sed -n '1,2p' /sys/module/lssbi_probe/parameters/fwft
cargo run -- --cpu 3

Security

Only an administrator can install or load lssbi_probe. Its exported values are non-secret firmware metadata and have mode 0444. As with every external kernel module, loading it marks the kernel with the out-of-tree (O) taint. Systems using kernel lockdown or mandatory module signatures may reject an unsigned module; use the distribution's DKMS signing workflow in that case.

License

The Rust program, build support, and documentation are available under either:

• MIT License
• Mulan PSL v2

The kernel probe is licensed under GPL-2.0-only and declares MODULE_LICENSE("GPL").