[Slackbuilds-users] [qemu-static] update-binfmts --import — intended manual step?

[Julian Grinblat]

> Doesn't the "runbook" give enough info on how to run aarch64 docker containers on x86_64 Slackware64, including running `update-binfmts --import`?

The commands are there, but what's missing is *why* `--import` is a
separate, necessary step: binfmt-support only re-enables formats
already recorded in /var/lib/binfmts, it doesn't scan
/usr/share/binfmts for new ones. So a user who already has
binfmt-support running fine can reasonably (and wrongly) assume
installing this package is enough on its own. I've included a small
patch below, which I think will be useful for newcomers:

--- a/README
+++ b/README
@@ -11,6 +11,11 @@
 If you have installed (and activated in /etc/rc.d/)
 the binfmt-support service, they will be loaded at machine start up.

+Note: update-binfmts --import (below) must be run once after installing
+or upgrading this package - binfmt-support only re-enables formats
+already recorded in /var/lib/binfmts, it does not scan /usr/share/binfmts
+for new ones.
+
 Then you should be able to run all compatible docker images through
 qemu emulation transparently.

As an aside, not part of this patch: I hit a build failure worth
flagging if you're aware of it - the bundled static glibc fails with
`OPEN_TREE_CLONE redefined [-Werror]` when built against the
experimental linux-7.1.x testing kernel line (kernel-headers-7.1.x)
rather than mainline -current. kernel-headers-7.1.x reformats some
mount.h flags to bit-shift notation, which collides with glibc's own
bundled definition of the same constant - harmless (same value), but
fatal since glibc's build enables -Werror. Slackware's own official
glibc build doesn't hit this, since it's built against mainline
kernel-headers, not the testing branch. --disable-werror on the
bundled glibc's configure works around it, in case it's useful to know
about even without a formal patch.

Thanks again for maintaining this.

On Sat, Jul 11, 2026 at 7:39 PM Lockywolf
<for_slackbuilds-users_mlist_2023-04-21 at lockywolf.net> wrote:
>
> Julian Grinblat <julian at dotcore.co.il> writes:
>
> > So it looks like update-binfmts --import has to be run manually, once,
> > after installing — matching the manual runbook in the package's own
> > README. Is that intentional?
>
> Yes, this is intentional.
> The point is that the SBo "tradition" is that builds only _install_
> packages, services, programs, modules, but don't "activate them by
> default", in order to avoid unintentionally damaging whatever fragile
> setup the user has.
>
> >If so, it might be worth adding a
> > one-line callout in the README, since it's easy to miss.
>
> I don't mind improving the README, but I am not exactly sure what is
> missing. Doesn't the "runbook" give enough info on how to run aarch64
> docker containers on x86_64 Slackware64, including running
> `update-binfmts --import` ?
>
> Could you send a git patch/diff with your intended improvement to my
> email, and I will gladly accept it, if it makes sense.
>
> --
> Your sincerely,
> Vladimir Nikishkin (MiEr, lockywolf)
> (Laptop)
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