Re: [gentoo-dev] Re: rfc: Does OpenRC really need mount-ro

[Richard Yao]

On 02/17/2016 01:32 PM, Rich Freeman wrote:
> On Wed, Feb 17, 2016 at 1:06 PM, Ian Stakenvicius <axs@g.o> wrote:
>>
>> Genkernel's initramfs generation was what we endorsed for the most
>> part, until dracut came around.  it's hard to say what "most" are
>> doing but i expect dracut and genkernel based initramfs's make up
>> the vast majority in use by gentoo users, with a small minority
>> rolling their own through other means.
>>
>
> While I personally endorse dracut over genkernel, the reality is that
> only genkernel is actually documented in the handbook.  This is due at
> least in part to laziness on my part as I've been meaning to add it
> since forever.
>
> Likewise I intend to update the handbook to make selection of
> openrc/systemd less convoluted as well.  The current handbook does
> offer systemd as an option but then basically refers you out to
> another page that doesn't follow the same flow as the handbook.
>
> In my notes I've found that it is a pretty trivial change to pick one
> or the other actually if you do it at the right time, so this could be
> added to the handbook with very little disruption to the flow for
> non-systemd users.  I imagine other service managers would be similar,
> or even simpler.  I found that switching between the two only requires
> two changes - one is to pick a systemd profile relatively early in the
> process before doing a world update, and then changing one line in
> your grub config at the end.  If you emerge world after you do most of
> your system configuration systemd will automatically pick up all the
> openrc configuration and use it, which as a bonus leaves you with a
> system that is easy to boot in either mode.
>
> Getting back to dracut - it is really just a few lines added as an
> alternative to the initramfs section.  After you build your kernel it
> is really just a one-liner, and grub2-mkconfig picks up on it
> automatically (as I imagine it probably does with genkernel as well).
> Unless you want to play with the configuration there isn't much fuss.

dracut does not assist those who do not want generic kernel
configurations. Unfortunately, the handbook does not do a good job in
saying that the initramfs generation and generic kernel configurations
are optional.

> I think we really should give strong consideration to recommending
> dracut as a default, while of course preserving the option of
> genkernel.  I'm certainly open to feedback if there is some use case
> where genkernel is better, but dracut is cross-distro, gives you
> options to easily maximize or minimize your config, and is really easy
> to tailor with modules.

There is no default and system boot without an initramfs not only works,
but is advisable for faster boot unless something fancy is being done
that needs it.

Claiming to pick a default between genkernel and dracut when both are
optional makes no sense, especially since dracut's capabilities
(initramfs generation) are a subset of genkernel's (initramfs generation
and kernel builds). dracut could replace genkernel's initramfs
generation capabilities, but it simply cannot replace genkernel for
building a generic kernel. It was never intended to do that.

By the way, pver the course of time, there have been things genkernel
did better and things dracut did better. It is unlikely one will ever be
superior to the other. However, some feedback on what genkernel does
poorly versus dracut and could therefore improve would be helpful.