Re: Question on BIGGEST_ALIGNMENT in GCC on NetBSD/m68k

[Greg Ungerer <gerg@kernel.org>]

On 19/6/25 08:29, Finn Thain wrote:
> On Wed, 18 Jun 2025, Greg Ungerer wrote:
>
> > > It's not really necessary to enforce this on Coldfire. However, since
> > > buildroot builds completely from source, it wouldn't even be a problem
> > > to change the alignment there as well.
> >
> > Yes, that is totally right in my experience. Certainly in my ColdFire
> > work it is pretty much always a build-everything approach via buildroot
> > or similar. I wouldn't think an ABI change would actually worry too many
> > ColdFire uses, they don't use distributions like debian on them. (I
> > would love to hear from anyone who does!).
>
> That may work for end-users with a vendor BSP. But upstream developers
> need to be able to swap components. In general, when debugging I often
> have to run old binaries to find out whether I'm dealing with a deeper
> regression or not. Also, there is the bisection problem. It's not just a
> couple of distros who get to pay for an ABI break. It's the entire
> ecosystem.

I am sure there is value in that for some. Like I said though
that has not been my experience with ColdFire. And by that I mean as
the upstream maintainer of ColdFire Linux support for +20 years.
I pretty mush _always_ build kernel + libs + user for testing even
small kernel changes. My standard small system build takes less
than 1 minute for everything. Again, I am just relating my experience
with this - admittedly probably not typical of actual end users.

FWIW even when I was working on shipping ColdFire based products
my firmware was always a complete update, no separate kernel and
user space updates. Typical of small embedded systems. I can't
actually remember many times I have run with a previously compiled
user space.

Regards
Greg