[PATCH v2 3/9] x86/cfi: Document the "cfi=" bootparam options

Kees Cook
2025-09-04T03:46:56Z

The kernel-parameters.txt didn't have a section for the cfi= options.
Add it.

Signed-off-by: Kees Cook <kees@kernel.org>
---
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: <linux-doc@vger.kernel.org>
---
Documentation/admin-guide/kernel-parameters.txt | 17 +++++++++++++++++
1 file changed, 17 insertions(+)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 747a55abf494..8bbffbb334ab 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -608,6 +608,23 @@
ccw_timeout_log [S390]
See Documentation/arch/s390/common_io.rst for details.

+ cfi= [X86-64] Set Control Flow Integrity checking features
+ when CONFIG_FINEIBT is enabled.
+ Format: feature[,feature...]
+ Default: auto
+
+ auto: Use FineIBT if IBT available, otherwise kCFI.
+ Under FineIBT, enable "paranoid" mode when
+ FRED is not available.
+ off: Turn off CFI checking.
+ kcfi: Use kCFI (disable FineIBT).
+ fineibt: Use FineIBT (even if IBT not available).
+ norand: Do not re-randomize CFI hashes.
+ paranoid: Add caller hash checking under FineIBT.
+ bhi: Enable register poisoning to stop speculation
+ across FineIBT. (Disabled by default.)
+ warn: Do not enforce CFI checking: warn only.
+
cgroup_disable= [KNL] Disable a particular controller or optional feature
Format: {name of the controller(s) or feature(s) to disable}
The effects of cgroup_disable=foo are:
--
2.34.1