[chasil]

This will particularly impact the "Red Hat Compatible Kernel" (RHCK) that is shipped by Oracle Linux.

https://docs.oracle.com/cd/E37670_01/E57668/html/ol_kern_65r...

Assuming that RHEL v8 strips BtrFS, Oracle's RHCK will have to add support back in, and thus no longer be "compatible." Without that support, some filesystems will fail to mount at boot. In-place upgrades from v7 to v8 will be problematic.

Oracle has worked very hard to maintain "compatibility" with Red Hat, even going so far as to accept MariaDB over MySQL. Their reaction to the latest "poison pill" will be interesting.

[lenzgr]

Why would Oracle have to add Btrfs support back into the RHCK? It's exactly the point of this kernel to be 100% identical to upstream RHEL. If an Oracle Linux user needs Btrfs support, it will still be included in the "Unbreakable Enterprise Kernel" (UEK), which Oracle provides as an alternative.

[chasil]

Any BtrFS filesystems in /etc/fstab won't mount if/when an RHCK boots that lacks the filesystem driver.

An in-place upgrade from v7 to v8 could easily get hosed.

[bonzini]

Does Oracle support Btrfs (as opposed to making it just a tech preview) with the compatible kernel? I don't think so, since it's the same code as RHEL. And if not, hosing in-place upgrades is acceptable. RHEL 7 is supported until 2024.