Re: [PATCH] samples: ftrace: replace bti assembly with hint for older compiler

On Sun, Aug 20, 2023 at 1:10 PM GONG, Ruiqi [off-list ref] wrote:

When cross-building the arm64 kernel with allmodconfig using GCC 9.4,
the following error occurs on multiple files under samples/ftrace/:

/tmp/ccPC1ODs.s: Assembler messages:
/tmp/ccPC1ODs.s:8: Error: selected processor does not support `bti c'

Fix this issue by replacing `bti c` with `hint 34`, which is compatible
for the older compiler.

I see this hint is already used in
tools/testing/selftests/arm64/fp/rdvl.S but I'm curious why it isn't
used in other parts of the kernel like
arch/arm64/kernel/entry-ftrace.S or
tools/testing/selftests/arm64/bti/syscall.S