Re: Dracut -- Cross distribution initramfs infrastructure

[Daniel Pittman <daniel@rimspace.net>]

Jeremy Katz <katzj@redhat.com> writes:
> On Dec 19, 2008, at 10:27 AM, Theodore Tso wrote:
>> On Fri, Dec 19, 2008 at 02:55:26PM +0100, Hannes Reinecke wrote:
>>>
>>> The goal of the initrd is to activate and mount the root fs.
>>> And the root fs _only_. Every other system should be configured
>>> once the main system is running.

[...]

>> There may also be times when it is useful to operate on the root
>> filesystem in some way before it is mounted; in most cases the
>> operation can bedone on a filesystem mounted read-only, yes --- but at
>> the cost of needing to reboot afterwards if the root filesystem needs
>> to be modified by said userspace tool.
>
> I think that once you start getting into this realm, though, you end
> up with an incredibly over-complicated and slow initramfs.  If we
> instead focus on keeping things "fast", the reboot afterwards isn't
> that costly.

One of the features of the Debian / Ubuntu initramfs infrastructure,
which sounds remarkably like your design (or vice-versa), is that it
drops all the "standard" drivers into the initramfs.

This is, to me, worth several minutes of additional boot time, in terms
of flexibility: being able to modify the hardware and be confident that
the appropriate drivers are in place already makes life much, much
easier.

(In practice I doubt this adds more than a second or five to boot time;
 certainly, it takes no longer to get to rootfs mounted than the RHEL 4
 systems that have nothing but what is essential in the initrd...)


So, it would certainly be my hope — with my systems administration hat
on — that your proposed system would support that similar operation as
an option, at least.

Personally, I think it makes the right default: better correct than
fast, but obviously tastes vary there.

Regards,
        Daniel