Do profile USE-flags change over time?

[lars_the_bear]

Hi folks

I set up two Gentoo machines about two months apart. I used what seemed to me to be identical procedures. I used the same profile in both cases (23.0 desktop/stable) and made the same global USE changes in /etc/portage/make.conf.

And yet...

On one machine, the newer one, 'emerge --info' shows I have USE=qml at the global level, while the earlier one does not. I don't set this flag (so far as I know), so I presume it is some kind of profile default.

This change is a big deal, because the Gentoo official binhost has a binary of qtwebengine that has '-qml', but not one that has 'qml' with my other USE-flag settings (again, so far as I know). I really don't have three days to spend building qtwebengine from source. So I've installed qtwebengine with 'USE=-qml', in the hope that this won't break anything. I have no idea what 'qml' is, so I don't know what the implications are likely to be. But fingers crossed.

My question is: is this change in USE flag explicable? Do the defaults on specific profiles change from time to time, even though the profile version has not? I kind-of thought that if I set up multiple installations with the same profile number and name, they would be identical. Have I made another terrible misjudgement?

BR, Lars.

[Nowa]

[lars_the_bear]

[Nowa]

[Ionen]

Profile default changes are also rather infrequent (can sometime go years without changes), albeit fwiw base desktop profiles should gain "wayland" soon as a default too (which gnome and plasma profiles already had).

[szatox]

[lars_the_bear]

[Nowa]

[szatox]

Run this and see how bad it's actually going to be in your case:

[lars_the_bear]

[quote="szatox"
On my system it wants to rebuild like 60 perl packages and reuse 1249 binary packages.
[/quote]

It's not that many for me. But my point is that I wanted to make the new system like the old one, not the other way around. I spent a lot of time -- weeks to months -- compiling stuff on that old machine, and I was really hoping to be able to reuse all the compiled packages on the new system. I don't even care if that means I end up using older versions, since the versions on my old system work well enough already for my purposes. But, in fact, the biggest problem isn't packages that have newer versions, but packages that have the same versions, but no longer match the profile USE flags.

So, in future, I guess what I need to do for a new installation is to look at the profile USE settings before doing much installation, and then fix them up so they match the USE settings on the host where I built the binaries.

It's not a show-stopper but, honestly, I was completely unprepared to find that profile defaults would change.

BR, Lars.

[szatox]

Hold on. Use flags are declarative. They're either on or off. Emerge does not consider system's history when matching them.
This means that your both systems using the same profile should have the same flags... Unless you're explicitly changing them on one of your machines.

This is different than alternative dependencies in virtual packages.
So, why don't your flags match? Did you change some in make.conf? Did they get auto-unmasked in package.use?
Or do you use an old portage tree on the old machine and a new tree on the new one?
_________________
Make Computing Fun Again

[lars_the_bear]

[Nowa]

[pingtoo]

[eschwartz]

[eschwartz]

[sam_]

And if they're your own binpkgs, not the official ones, you can change the qml default if you really want, ideally temporarily with p.use scoped to version.

[lars_the_bear]

Thanks. I don't want to waste anybody's time following this up -- I have worked around the problem (and perhaps if I had waited until the official binhost was updated, there might not even have been a noticeable problem).

I was just surprised, is all. i expected software packages to change after I installed one machine, and I was prepared to have to deal with that. I wasn't at all prepared for profile defaults to change, and that blew my mind.

[eschwartz]

[szatox]

[pjp]

[eschwartz]

[lars_the_bear]

Thank you all for the responses, but I remain completely confused about the best way to proceed.

I've complained repeatedly about the amount of compilation involved in running Gentoo, on ten-year-old laptops. Some packages take literally days to compile, and my choice of global USE flags (particularly -pulseaudio -wayland) means that the Gentoo official binhost is often not of much help.

So I thought I could build all the packages I want on one machine, and use it as a binhost for others. They all have similar hardware and the same USE settings. I really expected this to relieve me of a load of compilation.

And it worked fine, until yesterday, when I tried to install FreeCAD on a machine I was setting up. This required an installation of qtwebengine, which I'd already spent nearly four days building a couple months ago. So I really expected to be able to use my pre-existing binary on this new installation.

But I couldn't, because the binary was built on a system that did not have the 'qml' USE-flag set. My new installation -- based on the same profile and global settings as the old one -- does have this flag set. It wasn't set by me -- @eschwarz confirms that this was a deliberate change in the profile. I worked around the problem by adding USE=-qml to qtwebengine and, although I'm not sure what the implications are, FreeCAD seems to work fine, albeit using a version of qtwebengine from an incompatible set-up. I don't use Qt for anything else than FreeCAD, so I don't really care how broken it is in other respects.

I'm not sure whether what I've seen here -- unexpected profile changes -- is a weird and rare fluke, or something I have to be prepared to deal with on a regular basis. If profile USE flags can change at any time without warning, then the idea of using one machine as a binhost for later installations starts to look unattractive. I really did think this was going to help with my compilation burden, but perhaps not.

I've heard reference to 'stage 4' images and, although I don't fully understand what that entails, perhaps that's what I need rather than just a binhost? But I guess that's not going to help me with reducing the burden of regular updates.

So, in short, I'm still struggling to find a way to use Gentoo effectively on old hardware, and all the ways I try seem to have unforeseen problems. Well, unforeseen by me, anyway.

BR, Lars.

[Nowa]

[pietinger]