Re: [gentoo-dev] /usr vs. initramfs redux

[Samuli Suominen]

On 08/05/2011 04:12 PM, Marc Schiffbauer wrote:
> * Rich Freeman schrieb am 05.08.11 um 14:42 Uhr:
>> On Fri, Aug 5, 2011 at 6:16 AM, Marc Schiffbauer <mschiff@g.o> wrote:
>>> * Robin H. Johnson schrieb am 05.08.11 um 02:46 Uhr:
>>> [...]
>>>> That leaves the only reasonable solution as #2. In terms of minimal
>>>> impact, I propose that we offer users with a static system an absolutely
>>>> minimal initramfs, that _just_ mounts the required directories.  No
>>>> modules, no LVM, no MD, no crypto etc - if you want that functionality,
>>>> go and use genkernel or dracut. If your fstab contains a line like:
>>>> /dev/sdXN /usr ...
>>>> Then this initramfs is for you.
>>>>
>>>> The minimal initramfs would do the following.
>>>>
>>>> 1. Mount devtmpfs/sysfs/procfs as needed to access devices.
>>>> 2. Mount real_root to /newroot
>>>> 3. Read /newroot/etc/initramfs.mount and /newroot/etc/fstab
>>>> 4.1. If /newroot/etc/initramfs.mount does not exist
>>>>      Assume it contains only: /usr /var
>>>> 5. Mount the combined items from said files
>>>> 6. pivot_root.
>>>>
>>>
>>> That sounds like a good compromise to me!
>>
>> Why would we build yet another initramfs vs just making dracut work
>> reliably?  You can already build dracut without support for
>> lvm+raid+luks/etc.
>
> If dracut will have some sort of minimalistic mode where it would
> generate such an initrd that would be ok IMO.
>
> OTOH the initrd that Robin described would be a very static solution
> with almost no dependencies, so if genkernel had a USE flag like
> "dracut" it would be possible to build it without dracut
> dependency and thus would allow for smaller systems.
>
> -Marc

To clarify,

By dependencies in dracut you mean udev? And by smaller systems you mean
systems without udev?

Then yes, such minimal initramfs should propably be covered in the
embedded's documentation, but otherwise trying to avoid dracut is
reinventing the wheel...