`nova-drm` is scheduled to expose a user-space API to receive IOCTLs from user-mode drivers, and to call into `nova-core` to perform the actual work. We are about to reach the state where we need the ability to call into `nova-core`, but the current Rust build system does not support this, and the solution will likely take at least a couple of cycles to be merged.
In the meantime, this series introduces a Nova-local workaround for `nova-drm` to call into `nova-core`. It generates the `nova-core` metadata that `nova-drm` can use to resolve references at build-time, and also builds a list of exported symbols for symbol resolution when modules are loaded. Since Rust symbols are long, this work ran into the limits on symbol sizes `modpost` can handle. Thus, the first patch instructs the compiler to inline initializers for some Rust basic types to avoid those long symbol names when symbols from `nova-core` are exported. Interestingly, this also results in a smaller nova-core binary size [1]. The rest of the patches enable inter-module calls from nova-drm to nova-core. This series is based on `drm-rust-next`. The current revision includes the feedback received on v3. In particular, moving everything to `drivers/gpu/Makefile` simplifies things considerably, and I have tried to align more with what is done in `rust/Makefile`. [1] https://lore.kernel.org/all/[email protected]/ Signed-off-by: Alexandre Courbot <[email protected]> --- Changes in v4: - Build nova-core and nova-drm from `drivers/gpu/Makefile`. - Emit nova-core's crate metadata as a side-effect of its normal object build. - Align more closely with the rules of `rust/Makefile`. - Add `.gitignore` entries for generated files. - Inline a few more Rust methods per Sashiko's recommendation. - Drop a few `Reviewed-by`s as the implementation has changed significantly. - Link to v3: https://patch.msgid.link/[email protected] Changes in v3: - Drop the modpost overflow detection patch as it is to be merged through the KBuild tree. - Drop obsolete (and actually unnecessary) changes to `pin_init`. - Do not inline methods returning `impl PinInit` as they cannot contribute to the long symbol names problem. - Use `#[inline]` instead of `#[inline(always)]` for methods that could create excessively long symbols. - Link to v2: https://patch.msgid.link/[email protected] Changes in v2: - Rebase on top of HRT v5. - Inline some `pin_init` and Rust basic types methods to avoid long symbol names and optimize code. - Print truncating modpost symbols and abort upon meeting them. - Drop increase of `buf_printf`'s buffer. - Drop obsolete nova-core renaming patch. - Link to v1: https://patch.msgid.link/[email protected] --- Alexandre Courbot (6): rust: inline some init methods gpu: build nova-core and nova-drm from drivers/gpu/Makefile gpu: nova-core: export Rust symbols for nova-drm gpu: nova-core: emit Rust metadata for nova-drm gpu: drm: nova: build after nova-core and use its symbols [POC] gpu: drm: nova: demonstrate interaction with nova-core drivers/gpu/Makefile | 36 ++++++++++++++++++- drivers/gpu/drm/Makefile | 2 +- drivers/gpu/drm/nova/Makefile | 4 +-- drivers/gpu/drm/nova/driver.rs | 9 ++++- drivers/gpu/nova-core/.gitignore | 2 ++ drivers/gpu/nova-core/Makefile | 4 +-- drivers/gpu/nova-core/driver.rs | 59 +++++++++++++++++++++++-------- drivers/gpu/nova-core/gpu.rs | 9 +++-- drivers/gpu/nova-core/gsp/hal.rs | 2 +- drivers/gpu/nova-core/nova_core.rs | 4 +-- drivers/gpu/nova-core/nova_core_exports.c | 15 ++++++++ rust/kernel/alloc/kbox.rs | 2 ++ rust/kernel/init.rs | 2 ++ rust/kernel/sync/arc.rs | 4 +++ 14 files changed, 125 insertions(+), 29 deletions(-) --- base-commit: fea3a2dd7d3fc1936211ced5f84420e610435730 change-id: 20260430-nova-exports-502f996c5aab Best regards, -- Alexandre Courbot <[email protected]>
