[4/4] Introduce the kabi tool from Oracle and custom enhancements + documentation.

[casasnovas]

This pull-request adds a new tool, kabi, imported from the Oracle UEK sources. Modifications are
made to it to add an interactive interface augmented with many information required when handling
kABI changes, most notably:

• The list of our maintained binary drivers impacted by the kABI change
• The list of exported symbols modified by a particular type change
• The output of pahole for the original/rebased type
• The list of guilty commits leading to the type change

This PR includes extensive and almost exhaustive documentation on how to neutralize kABI changes.

This pull-request is the last in a series adding tools and documentation on maintaining
our dom0 kernel - for extra context, the final state can be seen here (the final README
especially):

https://github.com/xcp-ng/hypervisor-dev/tree/quentin-main

I've tried to split the changes into palatable/reviewable PRs, full list:

• [1/4] Add script and documentation to generate and refresh a symbol locked list. #2
• [2/4] Introduce the git-review-rebase tool as well as documentation on rebasing to latest upstream. #3
• [3/4] Add chapter on merging back changes from XenServer patch-queue. #4

[casasnovas]

To test the kabi tool, you can run:

cd /path/to/hypervisor-dev/repo/
( cd scripts/kabi ; pip install -e . )
kabi tui \
    --repository /path/to/linux/repo \
    --rev-list v4.19.19..origin/kernel/xcpng-4.19.325-cip129.8.0.44.1/base \
    --old-vmlinux ./kernel-abis/vmlinux-4.19.19.o \
    --new-vmlinux ./kernel-abis/vmlinux-4.19.325-cip129.o \
    --locked-file ./kernel-abis/xcpng-8.3-kabi_lockedlist \
    ./kernel-abis/Modules.kabi-4.19.19 ./kernel-abis/Symtypes.build-4.19.325-cip129

Note

The vmlinux.o files are included in the repo to allow reviewers to play with the tool and/or review the rebase without having to rebuild the original / modified kernel. They are stored with git lfs.

[fallen]

lgtm!

[casasnovas]

Thanks for all the reviews!!