NACK: [SRU][canonical-kernel-snap/main][kernel-snaps-uc24.04/pc][RFC PATCH v3 0/1] add nvidia-550 driver components

[Aaron Jauregui]

On Fri, Dec 13, 2024 at 03:02:02PM +1100, Aaron Jauregui wrote:
> [Changes between v2 and v3]
>   - cleaned up scripts and comments
>   - added better summaries/descriptions for components
>   - restructured hooks directory into per-component subdirectories
>   - shifted organize blocks to respective components
>   - replaced post-refresh hook copying with corresponding files in the
>     hooks directory (note: snapcraft did not support using symlinks for
>     this)
>   - updated [Impact] section with more detailed information
> 
> [Changes between v1 and v2]
> 
> kernel-snaps-u24.04:
>   - replaced TODO HACK FOR HOOKS
>   - updated nvidia userspace component type to standard
> 
> hooks:
>   - included install hook for the pc-kernel to install nouveau
>     component by default
> 
> [Impact]
> Snap components are a way to have optional content for snaps available
> for install without resorting to building a completely new snap. It's
> useful to think of them as lazy loading for snaps. Concretely, components
> are themselves snaps with locked-down functionality that are mounted
> within their parent snap's filesystem. Component revisions are tied 1 to
> 1 with their parent snap revision at upload time, meaning that any refresh
> also refreshes the components tied to the snap. This also means that
> components MUST be uploaded alongside the parent snap, or the store will
> reject the upload.
> 
> We use components here with the aim of providing a way for nvidia
> drivers to be selected for the pc-kernel without having to rebuild,
> targetting the nvidia-550 driver as a starting point with the aim of
> supporting more driver versions in the future. Since nouveau, currently
> included in the pc-kernel, conflicts with nvidia, we replace the nouveau
> .ko with a component compatible with the nvidia component scheme.
> 
> Images are intended to be built either with a nvidia graphics component
> either preloaded by being declared in the model, or at first boot, where the
> pc-kernel's install hook will detect that no nvidia graphics component exists
> and download nouveau. This should cover the uppgrade case for users of the
> existing pc-kernel that rely on nouveau. I am working on further functionality
> allowing for snap set to configure the desired graphics version and either
> configure it (if the component exists on disk) or to fetch it from the store.
> 
> The implemented components rely on install, refresh, and remove hooks
> for the respective functionality. These are intended to be placed in
> canonical-kernel-snaps. All 3 implemented components have a post-refresh hook
> that is identical to their install hook.
> 
>   - For the nvidia-ko and nouveau hooks, these hooks copy the corresponding
>     kernel modules to $SNAP_DATA/$(uname -r)/graphics, with the nvidia-ko hook
>     linking the modules and attaching their module signatures before moving
>     them. Both components' remove hooks delete the graphics directory. The
>     nouveau hooks are intended to be generic kernel module component hooks
>     with a special case for nouveau.
> 
>   - For the nvidia-user hooks, a directory corresponding to the kernel-gpu-2404
>     interface is created. A sentinel file is placed in the directory to be able
>     to notify the consumer of the kernel-gpu-2404 interface of file changes
>     (e.g. a refresh). All the libraries in the component are copied into this
>     directory. A mangler script is added for the consuming snap to have the
>     correct environment variables present when using the provided libraries.
> 
> Nvidia components are mostly self-contained, but a few changes to the pc-kernel
> snap were required. files/meta/kernel.yaml is required to enable kernel
> module support in snapd. The kernel-gpu-2404 content interface is
> declared for exposing nvidia userspace libraries, and is not intended to
> be accessed directly by users.
> 
> The current test plan on our end to my understanding includes smoke testing for
> both the ubuntu core use case and the hybrid case with tpm-backed fde (emulated
> through kvm, as hardware testing is currently not functional for tpm-backed 
> fde).  Cert should be in charge of testing beyond this, but I don't have much
> information about this yet. I should be able to confirm this and explain the
> test plan in better detail early next week.
> 
> [Test case]
> Nvidia components can be installed as follows:
> 
>  $ snap install pc-kernel+nvidia-550-ko pc-kernel+nvidia-550-user
> 
> The components install their files in $SNAP_DATA/modules/$(uname -r)/graphics
> 
> [Regression potential]
> There is potential for regressions to be introduced by the pc-kernel install
> hook, as it is executed on every install and and refresh event. If this
> script fails, the installation or update of the snap will abort.
> 
> Aaron Jauregui (1):
>   snapcraft.yaml: Add nvidia-550 and nouveau component support
> 
>  files/meta/kernel.yaml |   1 +
>  snapcraft.yaml         | 120 ++++++++++++++++++++++++++++++++++++++++-
>  2 files changed, 120 insertions(+), 1 deletion(-)
>  create mode 100644 files/meta/kernel.yaml
> 
> Aaron Jauregui (1):
>   nvidia-hooks: add hooks for nvidia kernel components
> 
>  hooks/module/install.module                   | 21 ++++++++++++++++
>  hooks/module/post-refresh.module              | 21 ++++++++++++++++
>  hooks/module/remove.module                    | 13 ++++++++++
>  hooks/nvidia-ko/install.nvidia-ko             | 25 +++++++++++++++++++
>  hooks/nvidia-ko/post-refresh.nvidia-ko        | 25 +++++++++++++++++++
>  hooks/nvidia-ko/remove.nvidia-ko              |  6 +++++
>  hooks/nvidia-user/install.nvidia-user         | 18 +++++++++++++
>  .../kernel-gpu-2404-provider-mangler          | 12 +++++++++
>  hooks/nvidia-user/remove.nvidia-user          | 10 ++++++++
>  hooks/pc-kernel/install.pc-kernel             |  6 +++++
>  hooks/pc-kernel/post-refresh.pc-kernel        |  6 +++++
>  11 files changed, 163 insertions(+)
>  create mode 100644 hooks/module/install.module
>  create mode 100644 hooks/module/post-refresh.module
>  create mode 100644 hooks/module/remove.module
>  create mode 100644 hooks/nvidia-ko/install.nvidia-ko
>  create mode 100644 hooks/nvidia-ko/post-refresh.nvidia-ko
>  create mode 100644 hooks/nvidia-ko/remove.nvidia-ko
>  create mode 100644 hooks/nvidia-user/install.nvidia-user
>  create mode 100644 hooks/nvidia-user/kernel-gpu-2404-provider-mangler
>  create mode 100644 hooks/nvidia-user/remove.nvidia-user
>  create mode 100644 hooks/pc-kernel/install.pc-kernel
>  create mode 100644 hooks/pc-kernel/post-refresh.pc-kernel

Superseded by v4 patchset on the mailing list