[Mageia-dev] mkinitrd and Mageia2

Colin Guthrie mageia at colin.guthr.ie
Fri Jan 27 11:02:25 CET 2012

'Twas brillig, and Charles A Edwards at 27/01/12 01:06 did gyre and gimble:
> It was my understanding that mkinitrd would continue to be supported in
> Mageia2 and then be phased out during the Mageia3 development.
> If this is the case, why is it that all 'current' kernels now
> require dracut?

Basically, if you want to use mkinitrd in mga2, you'll also have to use
sysvinit. I will not be supporting a systemd system with an mkinitrd initrd.

This is because systemd is fully hotplug, and thus does not just "try
and do things" and hope for the best. It waits until it knows devices
are available before using them. It does this via udev. If anything
mildly exotic is used (e.g. LVM, RAID etc.) then it is the initrd's job
to start these. If it's done in an mkinitrd, the metadata generated from
activating these devices is lost as udev is not running at the time. In
dracut, udev is running and critical metadata is saved and preserved for
systemd to use later.

So, with the background of why I will not support systemd+mkinitrd out
of the way, we have to look at the kernels themselves. We require dracut
now, but it's still perfectly possible to install mkinitrd and set the
alternatives up correctly such that it is used (update-alternatives
--display mkinitrd). If you do this, you are on your own - you need to
remember to install sysvinit and not let systemd be your init.

The original question is "why does the kernel require dracut?" Well,
it's our preferred initrd but, as mentioned above, you can still use
mkinitrd if you absolutely must, but you have to know the consequences
and repercussions. I originally made dracut fully obsolete mkinitrd,
giving no choice in the matter. This is still my preferred option for
mga2 if at all possible, but as I believe others want to keep it for
now, I'm fine with it. The kernel requires dracut to make sure that the
default init system (systemd) and the kernel initrd (made with dracut)
are paired.

Hope that answers your question.



Colin Guthrie

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