[PATCH v2 2/3] cpukit: Explicitly enforce alignment requirements

Kinsey Moore kinsey.moore at oarcorp.com
Tue Mar 2 21:41:58 UTC 2021

-----Original Message-----
From: Gedare Bloom <gedare at rtems.org> 
Sent: Tuesday, March 2, 2021 14:01
To: Kinsey Moore <kinsey.moore at oarcorp.com>
Cc: devel at rtems.org
Subject: Re: [PATCH v2 2/3] cpukit: Explicitly enforce alignment requirements

> On Tue, Mar 2, 2021 at 12:48 PM Kinsey Moore <kinsey.moore at oarcorp.com> wrote:
>> +/*
>> + * The use of explicit alignment is necessary below due to behavioral
>> + * expectations of GCC on which RTEMS has relied in the past. These
>> + * behaviors were consistent, but never guaranteed. Some newer platforms
>> + * violate this previous consistency. For more information, see GCC bug
>> + * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99143
>> + */
> I think the comment can be simplified, but I can tell you got bugged
> by this. (pun, intended)
> To summarize my understanding, GCC now optimizes space more
> aggressively, and if we want an explicit alignment, it has to be
> explicitly made on each variable that must be aligned. ("typedef"
> alignment now seems to be ignored.)

I'll trim it down in the next patch set.


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