[PATCH] docs/misra: add rule 2.1 exceptions

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

From: Stefano Stabellini <stefano.stabellini@xxxxxxx>

During the discussions that led to the acceptable of Rule 2.1, we
decided on a few exceptions that were not properly recorded in
rules.rst. Add them now.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxx>
---
 docs/misra/rules.rst | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/docs/misra/rules.rst b/docs/misra/rules.rst
index b6d87e076b..8f38227994 100644
--- a/docs/misra/rules.rst
+++ b/docs/misra/rules.rst
@@ -107,7 +107,18 @@ maintainers if you want to suggest a change.
    * - `Rule 2.1 
<https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_02_01_1.c>`_
      - Required
      - A project shall not contain unreachable code
-     -
+     - The following are allowed:
+         - Invariantly constant conditions, e.g. if(IS_ENABLED(CONFIG_HVM)) { 
S; }
+         - Switch with a controlling value statically determined not to
+           match one or more case statements
+         - Functions that are intended to be never referenced from C
+           code (e.g. 'do_trap_fiq')
+         - Unreachability caused by the certain macros/functions is
+           deliberate, e.g. BUG, assert_failed, panic, etc.
+         - asm-offsets.c, as they are not linked deliberately, because
+           they are used to generate definitions for asm modules
+         - declarations without initializer are safe, as they are not
+           executed
 
    * - `Rule 2.6 
<https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_02_06.c>`_
      - Advisory
-- 
2.25.1