Re: [Qemu-devel] [PATCH v4 7/10] qemu-binfmt-conf.sh: generalize CPU to positional TARGETS

[Unai Martinez Corral]

2019/3/11 a las 14:36, Laurent Vivier:
> On 11/03/2019 14:29, Unai Martinez Corral wrote:
> > 2019/3/11 12:14, Laurent Vivier:
> >> On 11/03/2019 11:30, Unai Martinez-Corral wrote:
> >
> >>> +-s|--systemd:                         don't write into /proc, generate 
> >>> file(s) for
> >>> +                                      systemd-binfmt.service; 
> >>> environment variable HOST_ARCH
> >>
> >> why HOST_ARCH appears here?
> >
> > The existing comment seems to be specific to systemd:
> > https://github.com/qemu/qemu/blob/master/scripts/qemu-binfmt-conf.sh#L201-L204
> > 'systemd' is the single mode in which it makes sense to generate a
> > bunch of configuration files for a different architecture than the
> > current one, isn't it?
>
> No, it's not specific to systemd. If we register an interpreter for the
> current architecture we can make it unusable.

I think we are not understanding each other in this point:

The comment about HOST_ARCH in the current master branch is as follows:

> With systemd, binfmt files are loaded by systemd-binfmt.service
>
> The environment variable HOST_ARCH allows to override 'uname' to generate
configuration files for a different architecture than the current one.

That's why I assumed that the envvar is meant to be used with systemd
only. Certainly, withou systemd no configuration files are generated
at all; interpreters are directly registered/configured.

However, the implementation takes HOST_ARCH into account with no
regard to 'systemd' or 'debian'. It is used unconditionally. This has
been like this since the base of the current script was pushed in
2016/1/29.

So, what is your proposal?

- Move the comment below, as it was before.
- Add a patch to only take HOST_ARCH into account for systemd (and debian?)
- Remove HOST_ARCH and the comment from the script (and take it back
if you patch to the kernel is accepted some day).

I will wait to sort this out before pushing v5. I think that all the
remaining issues are addressed already:
https://github.com/umarcor/qemu/blob/series-qemu-binfmt-conf/scripts/qemu-binfmt-conf.sh

Regards,
Unai