Add Intel graphics SRU exception page

[mckees]

Description

Previous review here:
https://code.launchpad.net/~mckeesh/sru-docs/+git/sru-docs/+merge/491986

This PR proposes a process for allowing full-stack upgrades for Intel GPU enablement in LTS releases. This is needed because aside from Mesa and the kernel, our LTS releases do not have support for new Intel hardware. This leaves important cases such as compute, media, and raytracing completely broken for products released over a year ago in Noble.

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Related issue

• Fixes: Migrate Intel Graphics SRU exception proposal to this repo #306

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Checklist

• I have read and followed the Ubuntu Project contributing guide
• My pull request is linked to an existing issue (if applicable)
• I have tested my changes, and they work as expected

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Additional notes (optional)

Changes made since previous upload:

• Add platform testing info and update versioning
• Remove hard 75% threshold for test devices
  • Change made after a discussion with @RAOF
• Fix spelling mistakes

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[mckees]

Just a quick note on the "linked issue (if applicable)" checklist item: I think it should always be applicable, given that the contributing guide requires us to create an issue if one does not exist. Though it is functionally an honesty/due diligence check for your first checklist item, so you may prefer to keep it as is :)

[basak]

Thank you for moving this across.

As well as https://code.launchpad.net/~mckeesh/sru-docs/+git/sru-docs/+merge/491986 that you linked there's also https://lists.ubuntu.com/archives/ubuntu-release/2025-February/006315.html and discussion over subsequent months, and https://wiki.ubuntu.com/IntelGraphicsUpdates. All should be checked for anything outstanding before landing this.

[RAOF]

I have reviewed this, and all the previous discussions, and I think that the current documentation satisfies all the concerns that have been raised.

I think this is good to approve.

[mckees]

Rebased the changes with no edits. The workflows previously failed the spellcheck due to the word "bootloader" being labeled as a misspelling in someone else's changes. If this happens again, can someone let me know if I should add it to the dictionary or if we can just merge with that workflow failing?

[RAOF]

Yay! Your rebase appears to have worked! (My one yesterday didn't?)