[xen staging] docs/misra: add Rule 5.1

[patchbot@xxxxxxx]

commit 8c1cc69748f4719e6ba8a275c2ecd60747c52c21
Author:     Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>
AuthorDate: Tue May 31 18:44:02 2022 -0700
Commit:     Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>
CommitDate: Tue Jun 7 17:44:03 2022 -0700

    docs/misra: add Rule 5.1
    
    Add Rule 5.1, with the additional note that the character limit for Xen
    is 40 characters.
    
    The max length identifiers found by ECLAIR are:
    
    __mitigate_spectre_bhb_clear_insn_start
    domain_pause_by_systemcontroller_nosync
    
    Both of them are 40 characters long.
    
    Explicitly mention that public headers might have longer identifiers.
    
    Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>
    Acked-by: Julien Grall <jgrall@xxxxxxxxxx>
---
 docs/misra/rules.rst | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/docs/misra/rules.rst b/docs/misra/rules.rst
index 7d6a9fe063..6ccff07765 100644
--- a/docs/misra/rules.rst
+++ b/docs/misra/rules.rst
@@ -82,6 +82,13 @@ existing codebase are work-in-progress.
      - Line-splicing shall not be used in // comments
      -
 
+   * - `Rule 5.1 
<https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_05_01_2.c>`_
+     - Required
+     - External identifiers shall be distinct
+     - The Xen characters limit for identifiers is 40. Public headers
+       (xen/include/public/) are allowed to retain longer identifiers
+       for backward compatibility.
+
    * - `Rule 6.2 
<https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_06_02.c>`_
      - Required
      - Single-bit named bit fields shall not be of a signed type
--
generated by git-patchbot for /home/xen/git/xen.git#staging