svn commit: r249734 - stable/9/sys/kern

[Mikolaj Golub]

On Thu, Apr 25, 2013 at 12:07:52AM +0200, Jeremie Le Hen wrote:
> Hi Mikolaj,
> 
> On Sun, Apr 21, 2013 at 05:14:50PM +0000, Mikolaj Golub wrote:
> > Author: trociny
> > Date: Sun Apr 21 17:14:50 2013
> > New Revision: 249734
> > URL: http://svnweb.freebsd.org/changeset/base/249734
> > 
> > Log:
> >   MFC r249238, r249239:
> >   
> >   r249238:
> >   
> >   Use 4-byte padding for core dump notes on both 32 and 64bit archs.
> >   
> >   Although native word padding (i.e. 8-byte on 64bit arch) looks to be
> >   in agreement with standards, other parts of our code and other OSes
> >   use 4-byte alignment.
> >   
> >   This is not expected to change alignment for currently generated core
> >   dump notes, as the notes look to consist of structures with sizes
> >   multiple of 8 on 64-bit archs. But there are plans to add additional
> >   notes, where 4-byte vs 8-byte alignment makes difference.
> >   
> 
> Sorry, I'm a little late, trying to catch up on emails.
> 
> I'd say this deserves a comment.  Even if you commit log clearly states
> the reason for this change, a casual reader may think it would be
> preferable to have native alignment and fix it without thinking of
> checking the SVN metadata.

Note, there are several places in this file where the padding is
used. Their amount has increased after r249486.

I thought about adding a constant

  #define ELF_NOTE_ROUNDSIZE	4

to imgactl_elf.c and using it throghthout the file. I think using '4'
explicetly (instead of sizeof(Elf32_Size)) should diminish confusion
about native alignment and the comment is not needed then.

What do you think about this?

-- 
Mikolaj Golub