APPLIED: [SRU][canonical-kernel-snaps/main][kernel-snaps-uc24.04/pc][PATCH 0/2] add configure hook, eol component support

Tue Jun 24 13:10:35 UTC 2025

On 17.06.25 06:05, Aaron Jauregui wrote:
> BugLink: https://bugs.launchpad.net/bugs/2114786
> 
> This covers two features: Support for EOL Nvidia driver components for the pc-kernel, and a configuration hook for the pc-kernel. These two bits of functionality are unfortunately quite closely intertwined, thus placed together.
> 
> [Impact]
> Add a configure hook to the pc-kernel snap to be able to switch between
> installed graphics drivers on a system. This gives the system the
> ability to switch between multiple installed graphics components without
> having to reinstall (and re-pull from store) the selected driver if it's
> already present. Drivers can be selected manually with snap set
> nvidia-stream=<driver> and selection is intended to be done by
> ubuntu-drivers once components are available on hybrid.
> 
> EOL components are also handled by this hook. Installed components are
> checked for an "eol" file after being installed. If one is found, the
> component number specified inside the eol file is installed. This
> behaviour is also triggered if an existing eol component is loaded.
> 
> Implement a preprocessing script to allow the snapcraft.yaml to shift
> along with the changes and updates in streams as new streams are added
> and old streams are EOL'd. Snap does not have a built-in concept of EOL
> or a mechanism to handle this case. Shifting to a template preprocessing
> model to build the snapcraft.yaml, along with the configure hook to handle
> behaviour at runtime, allows for new and EOL drivers to be specified with
> much less hassle.
> 
> [Fix]
> Configure hook installs components based off the nvidia-stream snap
> variable by pulling nvidia-<nvidia-stream>-ko and
> nvidia-<nvidia-stream>-server. Setting nvidia-stream to nouveau triggers
> a special case where only the nouveau-ko component is installed. If
> components are already on the system they are "loaded" into the graphics
> directory by rerunning their install hook.
> 
> If a non-supported value is provided the script will fail and
> no changes will be made to the system or the previous value of
> nvidia-stream. Also changed generic module install hook to follow symlinks
> when installing graphics drivers to support rerunning install hook.
> 
> Nvidia component streams are read from the new file nvidia_streams. Each
> line of nvidia_streams contains either a single stream version or an EOL
> stream and the target replacement version separated by whitespace. e.g.:
> 550
> 549 580
> Where 550 is valid and 549 is EOL and to be upgraded to 580. EOL components
> contain a single file named "eol" containing the replacement stream number.
> The logic to handle installation of the new driver components is handled by
> the configure hook.
> 
> If the preprocessing script is not run, the snapcraft.yaml is still
> valid and will build as normal (assuming existing templated values are
> resolved) with a nouveau component and no Nvidia driver components.
> 
> [Test case]
> Built, booted, verified installing all specified components (through the
> configure hook) in the following configurations:
> 
> - No preprocessing script, only nouveau present
> - With 550-erd components, generated by the preprocessing script
> - With 550-erd, 570-erd, and 549-erd (EOL, pointing at 570-erd) generated
>    by the preprocessing script.
> 
> In all of these cases, installing drivers from the store as well as switching
> currently installed drivers was tested for all listed component sets.
> 
> [Where things could go wrong]
> The pc-kernel configure hook runs on every install by default, analogous
> to an install hook. Note that if nvidia-stream is set to an invalid
> value and the pc-kernel is refreshed the configure hook will fail and
> cause the entire pc-kernel refresh to fail.
> 
> The configure hook is entirely optional on ubuntu core and will do
> nothing if nvidia-stream is not set.
> 
> The templating logic is purely for builds and thus does not affect any
> runtime behaviour.
> 
> Aaron Jauregui (2):
>    snapcraft.yaml: add pc-kernel configure hook
>    snapcraft.yaml: Template support for Nvidia components
> 
>   nvidia-templates/comp-tmpl     |  11 ++++
>   nvidia-templates/eol-comp-tmpl |   9 +++
>   nvidia-templates/eol-part-tmpl |  19 ++++++
>   nvidia-templates/part-tmpl     |  81 ++++++++++++++++++++++++++
>   nvidia_streams                 |   1 +
>   snapcraft.yaml                 | 103 +++++----------------------------
>   snapcraft.yaml.gen             |  37 ++++++++++++
>   7 files changed, 171 insertions(+), 90 deletions(-)
>   create mode 100644 nvidia-templates/comp-tmpl
>   create mode 100644 nvidia-templates/eol-comp-tmpl
>   create mode 100644 nvidia-templates/eol-part-tmpl
>   create mode 100644 nvidia-templates/part-tmpl
>   create mode 100644 nvidia_streams
>   create mode 100755 snapcraft.yaml.gen
> 
> Aaron Jauregui (1):
>    nvidia-hooks: add pc-kernel configure hook
> 
>   hooks/module/install.module         |  4 ++--
>   hooks/module/post-refresh.module    |  4 ++--
>   hooks/pc-kernel/configure.pc-kernel | 37 +++++++++++++++++++++++++++++
>   3 files changed, 41 insertions(+), 4 deletions(-)
>   create mode 100755 hooks/pc-kernel/configure.pc-kernel
> 

Applied to canonical-kernel-snaps/main and kernel-snaps-uc24.04/pc. Thanks.

-Stefan
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