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List:       grub-devel
Subject:    [MULTIBOOT2 DOC PATCH v2 09/11] multiboot2: Add C structure members alignment and padding considerat
From:       Daniel Kiper <daniel.kiper () oracle ! com>
Date:       2016-11-24 20:40:08
Message-ID: 1480020010-18421-10-git-send-email-daniel.kiper () oracle ! com
[Download RAW message or body]

Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
---
v2 - suggestions/fixes:
   - rephrase whole section
     (suggested by Andrew Cooper).
---
 doc/multiboot.texi |   11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/doc/multiboot.texi b/doc/multiboot.texi
index 9461890..fe134bc 100644
--- a/doc/multiboot.texi
+++ b/doc/multiboot.texi
@@ -1391,6 +1391,7 @@ document, but are included for prospective operating system and boot
 loader writers.
 
 @menu
+* C structure members alignment and padding consideration::
 * Notes on PC::                 
 * BIOS device mapping techniques::  
 * Example OS code::             
@@ -1398,6 +1399,16 @@ loader writers.
 @end menu
 
 
+@node C structure members alignment and padding consideration
+@section C structure members alignment and padding consideration
+
+It is preferred that the structures used for communication between the bootloader
+and the OS image conform to chosen ABI for a given architecture. If it is not
+possible then GCC @samp{__attribute__ ((__packed__))} (or anything else which has
+similar meaning for chosen C compiler) have to be added to relevant structures
+definitions to avoid spurious, in this case, padding and alignment.
+
+
 @node Notes on PC
 @section Notes on PC
 
-- 
1.7.10.4


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