Please refactor plymouth to remove the libdrm2 dependency when text themes are used

[Emmet Hikory]

The Ubuntu Core image contains libdrm2 and various implementations of userspace interfaces for specific DRI modules, which may not match hardware on target systems, especially for users intending not to provide any graphical interface (often including no graphical console). This significantly increases the size of the image, without direct benefit to the user.

plymouth should detect when the theme requires the direct rendering interface, and only load the appropriate DRM implementations at that time. The theme packages should depend on any required interfaces, and the plymouth package not require any DRM implementation when using text themes.

[Steve Langasek (vorlon)]

Correct in principle, awkward to implement in practice. Should definitely be discussed with upstream.

It looks to me like all four of the drm drivers combined add up to 476KB installed. Is this actually significant for Ubuntu Core in practice?

Currently ubuntu-core images are only built for armel. As a first pass, would it be a good idea to evaluate whether some of these DRM backends should be dropped for armel? E.g., does it ever make sense to build libdrm-intel1 for the armel architecture?

[Emmet Hikory (persia)]

The last image I checked was about 100MB, so the DRM implementations represent less than 1%, although anything that can be removed from this is interesting, as 100MB is considered "very large" when compared to other base rootfs environments made available by other projects (e.g. TLIB).

In principle, there's no reason that Core couldn't be built for other architectures: although nobody has yet volunteered to care for the images for other than armel.

I'd be opposed to attempting to trim packages on an architecture-specific basis: while there are no current chipsets available that use Intel DRI and armel, there are always discussions surrounding any new SoC design, and Intel has previously produced devices supporting ARM instruction sets. Further, there are devices supporting ARM instruction sets that allow attachment of external bus devices, such as PCIe: while Intel does not currently produce a discrete graphics solution, there have been persistent rumours of such devices for several years. I believe there exists available hardware for all other included DRM implementations for all architectures currently in Ubuntu.