[PATCH v3 0/5] gpu: drm: nova: enable calling into nova-core

[Alexandre Courbot]

`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`.

[1] https://lore.kernel.org/all/DIN76NTFEU1N.1RT6G4IFD62RG@xxxxxxxxxx/

Signed-off-by: Alexandre Courbot <acourbot@xxxxxxxxxx>
---
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@xxxxxxxxxx

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@xxxxxxxxxx

---
Alexandre Courbot (5):
      rust: inline some init methods
      gpu: nova-core: export Rust symbols for dependent modules
      gpu: nova-core: emit Rust metadata for dependent modules
      gpu: drm: nova: build after nova-core metadata
      [POC] drm: nova: demonstrate interaction with nova-core

 drivers/gpu/drm/nova/Makefile             | 15 ++++++++
 drivers/gpu/drm/nova/driver.rs            |  9 ++++-
 drivers/gpu/nova-core/Makefile            | 48 ++++++++++++++++++++++++-
 drivers/gpu/nova-core/driver.rs           | 59 +++++++++++++++++++++++--------
 drivers/gpu/nova-core/gpu.rs              |  9 +++--
 drivers/gpu/nova-core/nova_core.rs        |  4 +--
 drivers/gpu/nova-core/nova_core_exports.c | 13 +++++++
 rust/kernel/alloc/kbox.rs                 |  2 ++
 rust/kernel/init.rs                       |  1 +
 rust/kernel/sync/arc.rs                   |  2 ++
 10 files changed, 141 insertions(+), 21 deletions(-)
---
base-commit: 0e42ec83d46ab8877d38d37493328ed7d1a24de8
change-id: 20260430-nova-exports-502f996c5aab

Best regards,
--  
Alexandre Courbot <acourbot@xxxxxxxxxx>