[PATCH 2/2] docs/misra: add Rule 5.1

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

From: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>

Add Rule 5.1, with the additional note that the character limit for Xen
is 63 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. A limit of 63 characters work for
the existing code.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>
---
 docs/misra/rules.rst | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/docs/misra/rules.rst b/docs/misra/rules.rst
index c0ee58ab25..6052fc6309 100644
--- a/docs/misra/rules.rst
+++ b/docs/misra/rules.rst
@@ -35,6 +35,11 @@ hypervisor.
   - Severity:  Required
   - Summary:  Line-splicing shall not be used in // comments
   - Link:  
https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_03_02.c
+- Rule: Rule 5.1
+  - Severity:  Required
+  - Summary:  External identifiers shall be distinct
+  - Link:  
https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_05_01_2.c
+  - Note: the Xen characters limit for identifiers is 63
 - Rule: Rule 6.2
   - Severity:  Required
   - Summary:  Single-bit named bit fields shall not be of a signed type
-- 
2.25.1