[OpenWrt-Devel] Migration in ath79 for swapped ethernet

Adrian Schmutzler mail at adrianschmutzler.de
Tue Jan 28 10:48:28 EST 2020

Hi Piotr,

> -----Original Message-----
> From: openwrt-devel [mailto:openwrt-devel-bounces at lists.openwrt.org] On
> Behalf Of Piotr Dymacz
> Sent: Montag, 27. Januar 2020 21:45
> To: Adrian Schmutzler <mail at adrianschmutzler.de>
> Cc: openwrt-devel at lists.openwrt.org; gch981213 at gmail.com;
> ansuelsmth at gmail.com; 'David Bauer' <mail at david-bauer.net>
> Subject: Re: [OpenWrt-Devel] Migration in ath79 for swapped ethernet
> Hi Adrian,
> On 27.01.2020 19:35, Adrian Schmutzler wrote:
> > Just a quick one:
> >
> >> > So, no matter what we do, there is no easy way forward.
> >>
> >> We could remove all ar71xx -> ath79 migration helper scripts, ar71xx
> >> board names from supported devices lists in ath79 images and make the
> >> target a brand new, without any concerns about soon-to-be obsolete ar71xx
> >
> > At the moment, I'm actually mostly inclined towards this solution.
> I'm afraid it's a bit late for that as 19.07 is already out and it
> supports (at least partially) ar71xx -> ath79 migration path/s.
> Wouldn't that look unprofessional? Am I overreacting here?

One didn't have to use -F during sysupgrade, but the release notes gave the
clear advice to upgrade without keeping settings.
So, IMO we actually didn't "support" any migration in 19.07.0.

> > However, for me personally SUPPORTED_DEVICES was always more a "don't
> brick entirely" flag, so I never expected it to ensure 100 % config
> More like preventing me from flashing ubnt,unifi image onto
> This impression might have been wrong, though.
> I think device to image matching was the main reason behind the idea.
> IIRC, mismatched image doesn't prevent you against upgrading with
> preserved settings.
> > But as mentioned by Ansuel, there are other incompatible switches to come
> (and some are already waiting), and unless we want to create new targets or
> rename devices in these cases, we have to think about different "levels" of
> compatibility anyway beyond ar71xx->ath79.
> I believe ar71xx -> ath79 is a special case here. First of all, that's a
> new DTS-enabled target and it was suppose to _replace_ ar71xx but 19.07
> went out with both of them and I'm pretty sure there are users who got
> confused with that (some devices are supported only in one of the
> targets, some in both, some with seamless migration possible). On the
> other hand, when ar71xx gets abandoned, we (as a project) should make it
> clear if ath79 is a replacement (thus providing seamless upgrade from
> ar71xx) or a new target, without any relationship with ar71xx (thus a
> clean sysupgrade is required). Keeping anything in between would just
> confuse people.

I do not really see a viable/desirable option to support eth migration at the
moment. And I'm not really a fan of adding lots of migration stuff which spoils
the new ath79 target already, so after all I think I also do not _want_ to add
eth migration either.

So, I'd prefer to see the ath79 new and clean.

However, from the wording perspective, I do not think that a "replacement" means
seamless upgrade. I'd thus keep the SUPPORTED_DEVICES just as a device-matching
measure, but wouldn't implement any sophisticated migration despite that. Having
SUPPORTED_DEVICES might actually be valuable for certain third parties, like I'm
involved in a downstream project that regenerates the system/network config at
each upgrade, but still exploits SUPPORTED_DEVICES for having the correct image.

And I could well live with keeping the already present migration scripts, as
having them as "undocumented feature" won't hurt. If we do not advertise it, it
won't confuse people ...



> DSA is slightly different topic as it will touch many different targets
> (also ath79, think about qca8k) so probably a project-wide solution
> would be required.
> --
> Cheers,
> Piotr
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