Re: [Buildroot] [PATCH v3 2/3] package/dracut: new host package

[Thierry Bultel <thierry.bultel@linatsea.fr>]

Le 06/01/2022 à 16:13, Thomas Petazzoni a écrit :
> On Thu, 6 Jan 2022 15:56:32 +0100
> Thierry Bultel <thierry.bultel@linatsea.fr> wrote:
>
>> Keeping in mind that systemd is the officially supported init system by
>> dracut, there is no extra work
>> for it. However, I brought support for busybox init, through the above
>> dracut module (05busybox-buildroot).
>> Adding support for the other ones could be done later, so I suggest we
>> simply disable dracut when the
>> init system is not supported; by adding
>>
>>       depends on !BR2_INIT_SYSV
>>       depends on !BR2_INIT_OPENRC
>>
>> in Config.in.host; with the appropriate comment. Does that sound
>> acceptable ?
> But is it just the init system that requires those special dracut
> "modules" ? Or other aspects of the system will also require some
> special modules ?

The dracut modules are used at build time.
The rule is that any file that is expected in the dracut image must be 
handled
by a dracut module. For instance,
"host/lib/dracut/modules.d/00bash"
"host/lib/dracut/modules.d/50sshd" work out of the box.

The implicitely loaded "90kernel-modules" (that check modules 
dependencies to one another,
and to firmwares) also work fine.

But nothing handles /etc/init.d/rcS, typically.
And all the wanted init scripts (/etc/init.d/S40network is a good example)
must be taken individually.
A huge work would be to contribute to dracut to bring whole support for 
initd
scripts, but I think it is out of the scope.

Another reason to write a module is when dracut does not support the 
feature, yet,
for instance, I had to write one for hostapd. Apparently it is not a 
common case
to have the wifi in an initramfs, but for a recovery system, that makes 
more sense.

Adding support for SYSV or OPENRC basically consists in writing the 
appropriate rules
in new modules to bring the expected files to the filesystem, nothing more.

By the way, my suggestion to use "depends on !xxx" directives cannot
work because it does an "unmet direct dependency detected", since
BR2_PACKAGE_HOST_DRACUT is selected by BR2_TARGET_ROOTFS_CPIO_DRACUT

I am a little bit confused about how to solve that properly.

Thierry

> Thomas


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