Re: [PATCH v9 0/6] gpu: nova-core: expose the logging buffers via debugfs

["Eliot Courtney" <ecourtney@nvidia.com>]

On Mon Mar 16, 2026 at 2:57 PM JST, Timur Tabi wrote:
> GSP-RM writes its printf message to "logging buffers", which are blocks
> memory allocated by the driver.  The messages are encoded, so exposing
> the buffers as debugfs entries allows the buffers to be extracted and
> decoded by a special application.
>
> When the driver loads, a /sys/kernel/debug/nova_core root entry is
> created.  To do this, the normal module_pci_driver! macro call is
> replaced with an explicit initialization function, as this allows
> that debugfs entry to be created once for all GPUs.
>
> Then in each GPU's initialization, a subdirectory based on the PCI
> BDF name is created, and the logging buffer entries are created under
> that.
>
> This series depends on Eliot Courtney's Cmdq patch set [1].
>
> Note: the debugfs entry has a file size of 0, because debugfs defaults
> a 0 size and the Rust abstractions do not adjust it for the same of
> the object.  Nouveau makes this adjustment manually in the driver.
>
> Signed-off-by: Timur Tabi <ttabi@nvidia.com>
> Tested-by: John Hubbard <jhubbard@nvidia.com>
>
> [1] https://lore.kernel.org/all/20260310-cmdq-locking-v4-0-4e5c4753c408@nvidia.com/
>
> Changes since v8:
> 1. Added #inline to Device::name()
> 2. Fixed rustfmt issues again
> 3. Updated write_to_slice()
> 4. Dropped "use pin projection in method boot()"
> 5. Now depends on Eliot's Cmdq patch set
> 6. Misc nits fixed
>
> Timur Tabi (6):
>   rust: device: add device name method
>   rust: uaccess: add write_dma() for copying from DMA buffers to
>     userspace
>   rust: dma: implement BinaryWriter for CoherentAllocation<u8>
>   gpu: nova-core: Replace module_pci_driver! with explicit module init
>   gpu: nova-core: create debugfs root in module init
>   gpu: nova-core: create GSP-RM logging buffers debugfs entries
>
>  drivers/gpu/nova-core/gsp.rs       | 49 ++++++++++++++---
>  drivers/gpu/nova-core/nova_core.rs | 50 +++++++++++++++++-
>  rust/helpers/device.c              |  5 ++
>  rust/kernel/device.rs              | 11 ++++
>  rust/kernel/dma.rs                 | 35 ++++++++++++-
>  rust/kernel/uaccess.rs             | 84 ++++++++++++++++++++++++++----
>  6 files changed, 213 insertions(+), 21 deletions(-)
>
>
> base-commit: a544873ce0575b2fd8285a1364d3e09929d9a3ba
> prerequisite-patch-id: fefd403caf8af386276351dd12397dda8ae8553f
> prerequisite-patch-id: 3e02192944c4dde97e6895a28371479aa49ddc96
> prerequisite-patch-id: de85fb30b65233210512b8295d7fe811f485f03f
> prerequisite-patch-id: 4232928e15093c74aa6d2a6519a4d7ac5e109607
> prerequisite-patch-id: d4f34f7eda8f5dcad2464f1bf3789e78556eb51c

Tested-by: Eliot Courtney <ecourtney@nvidia.com>