This series extends the Rust module! macro with three capabilities that
are available to C modules but currently missing from the Rust
abstractions: string parameters, early boot command-line parameters, and
configurable initcall levels.
The existing Rust module parameter infrastructure supports integer types
(i8..u64, isize, usize) but has no way to accept string values.
Additionally, built-in Rust modules cannot register parameters for early
boot command-line parsing (__setup / early_param), and all Rust modules
are hard-coded to initcall level 6 (device_initcall) with no way to
control initialization ordering.
String parameter support (patches 1-3):
Introduce StringParam, a Copy wrapper around *const c_char whose
memory is managed by the kernel parameter subsystem. Wire it into
the module! macro as the `string` parameter type with a dedicated
kernel_param_ops (PARAM_OPS_STRING) that stores the pointer directly
into a SetOnce<StringParam> container. The rust_minimal sample is
updated to demonstrate usage.
An earlier implementation of string parameter support was proposed in:
https://github.com/Rust-for-Linux/linux/pull/110/
This series takes a different approach for StringParam by storing the
raw C string pointer directly rather than copying the string data,
since the kernel guarantees the backing memory remains valid for the
module's lifetime. This avoids allocation in the parameter setter and
keeps StringParam as a simple Copy type consistent with the existing
integer parameter design.
Early boot parameter support (patches 4-7):
Add ObsKernelParam (mirroring the C obs_kernel_param), extend the
ModuleParam trait with from_setup_arg() for constructing parameter
values from raw __setup callback arguments, and integrate an optional
`early_param` field into the module! macro. When specified, the macro
emits a __setup entry in the .init.setup ELF section, gated behind
#[cfg(not(MODULE))] since this mechanism is only meaningful for
built-in modules.
Configurable initcall levels (patch 8):
Add an optional `initcall` field to the module! macro that accepts
any of the eight standard levels (pure through late). The default
remains level 6 (device) so existing modules are unaffected.
Matthew Wood (8):
rust: module_param: add StringParam type for C string parameters
rust: module_param: wire StringParam into the module! macro
samples: rust_minimal: demonstrate string module parameter
rust: module_param: add ObsKernelParam type
rust: module_param: add from_setup_arg() to ModuleParam trait
rust: macros: add early_param support to module! macro
samples: rust_minimal: demonstrate early_param usage
rust: macros: add configurable initcall levels to module! macro
rust/kernel/module_param.rs | 160 +++++++++++++++++++++++++++++++
rust/macros/lib.rs | 9 ++
rust/macros/module.rs | 179 +++++++++++++++++++++++++++++++++--
samples/rust/rust_minimal.rs | 33 ++++++-
4 files changed, 368 insertions(+), 13 deletions(-)
--
2.52.0
