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

[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:
> 
>>> +        if [ "$unknown_target" = "true" ] ; then
>>
>>            if [ "x$cpu" != "x$target" ] ; then
> 
> My bad. I fixed it before squashing, and broke it again when doing it.
> 
>>> +-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've proposed sometime ago a kernel patch to set binfmt_misc
configuration by namespace to avoid this kind of problem but it has
never been merged:

  [v6,0/1] ns: introduce binfmt_misc namespace
  https://patchwork.kernel.org/cover/10634807/

Thanks,
Laurent