`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/DIN76NTFEU1N.1RT6G4IFD62RG@nvidia.com/
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
---
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/20260530-nova-exports-v3-0-1202aa339ef7@nvidia.com
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/20260527-nova-exports-v2-0-06de4c556d55@nvidia.com
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/20260430-nova-exports-v1-0-7ca31664e983@nvidia.com
---
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 <acourbot@nvidia.com>