Date: Thu, 25 Apr 2013 09:20:20 +0300 From: Mikolaj Golub <to.my.trociny@gmail.com> To: Jeremie Le Hen <jlh@FreeBSD.org>, src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-9@freebsd.org Subject: Re: svn commit: r249734 - stable/9/sys/kern Message-ID: <20130425062018.GA74007@gmail.com> In-Reply-To: <20130424220752.GA2622@caravan.chchile.org> References: <201304211714.r3LHEo0R075715@svn.freebsd.org> <20130424220752.GA2622@caravan.chchile.org>
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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
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