Re: [PATCH 0/8] linker-section array fix and clean ups

[Jessica Yu]

+++ Johan Hovold [23/11/20 11:39 +0100]:
> On Fri, Nov 13, 2020 at 03:18:36PM +0100, Johan Hovold wrote:
> > On Wed, Nov 11, 2020 at 04:47:16PM +0100, Jessica Yu wrote:
> >
> > > Thanks for providing the links and references. Your explanation and
> > > this reply from Jakub [1] clarified things for me. I was not aware of
> > > the distinction gcc made between aligned attributes on types vs. on
> > > variables. So from what I understand now, gcc suppresses the
> > > optimization when the alignment is specified in the variable
> > > declaration, but not necessarily when the aligned attribute is just on
> > > the type.
> > >
> > > Even though it's been in use for a long time, I think it would be
> > > really helpful if this gcc quirk was explained just a bit more in the
> > > patch changelogs, especially since this is undocumented behavior.
> > > I found the explanation in [1] (as well as in your cover letter) to be
> > > sufficient. Maybe something like "GCC suppresses any optimizations
> > > increasing alignment when the alignment is specified in the variable
> > > declaration, as opposed to just on the type definition. Therefore,
> > > explicitly specify type alignment when declaring entries to prevent
> > > gcc from increasing alignment."
> >
> > Sure, I can try to expand the commit messages a bit.
>
> I've amended the commit messages of the relevant patches to make it more
> clear that the optimisation can be suppressed by specifying alignment
> when declaring variables, but without making additional claims about the
> type attribute. I hope the result is acceptable to you.
>
> Perhaps you can include a lore link to the patches when applying so that
> this thread can be found easily if needed.

Hi Johan,

Good idea, I've included a link to this thread for each patch.
I've queued up patches 3, 4, 6, 7, 8 for testing before pushing them
out to modules-next.

Thanks!

Jessica