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. 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. Changes since v3: 1. Implement a LookupDir struct instead of adding lookup methods to Dir. 2. Adds a Directory trait that is implemented by both LookupDir and Dir. 3. Creates DynParent enum to wrap both LookupDir and Dir. 4. No longer tries to "fix" Scope or scoped_dir. Alexandre Courbot (1): gpu: nova-core: implement BinaryWriter for LogBuffer Timur Tabi (8): rust: pci: add PCI device name method gpu: nova-core: Replace module_pci_driver! with explicit module init gpu: nova-core: use pin projection in method boot() rust: debugfs: implement Directory trait for Dir rust: debugfs: wrap Entry in an enum to prep for LookupDir rust: debugfs: add LookupDir gpu: nova-core: create debugfs root when driver loads gpu: nova-core: create GSP-RM logging buffers debugfs entries drivers/gpu/nova-core/gsp.rs | 68 +++++++++++-- drivers/gpu/nova-core/gsp/boot.rs | 14 +-- drivers/gpu/nova-core/nova_core.rs | 32 ++++++- rust/kernel/debugfs.rs | 148 ++++++++++++++++++++++++++++- rust/kernel/debugfs/entry.rs | 100 ++++++++++++++++++- rust/kernel/pci.rs | 37 ++++++++ 6 files changed, 377 insertions(+), 22 deletions(-) base-commit: 654826aa4a8f25cf825ad9254f37e6cb5092098f -- 2.52.0
