* Andy Lutomirski:

Also, I don't think there's any actual requirement that the upstream
kernel recognize existing CET-enabled RHEL 8 binaries as being
CET-enabled.  I tend to think that RHEL 8 jumped the gun here.

The ABI was supposed to be finalized and everyone involved thought it
had been reviewed by the GNU gABI community and other interested
parties.  It had been included in binutils for several releases.

From my point of view, the kernel is just a consumer of the ABI.  The

kernel would not change an instruction encoding if it doesn't like it
for some reason, either.

While the upstream kernel should make some reasonble effort to make
sure that RHEL 8 binaries will continue to run, I don't see why we
need to go out of our way to keep the full set of mitigations
available for binaries that were developed against a non-upstream
kernel.

They were developed against the ABI specification.

I do not have a strong opinion what the kernel should do going forward.
I just want to make clear what happened.

Thanks,
Florian