Re: [gentoo-dev] udev and /usr

[Joost Roeleveld <joost@antarean.org>]

On Thursday, September 15, 2011 09:27:06 AM Zac Medico wrote:
> On 09/15/2011 09:04 AM, Joost Roeleveld wrote:
> > Thank you for your response, however, I do have a few questions about
> > this. Where will this default initramfs actually need to be placed?
> 
> It should be similar to how sys-apps/v86d is used for uvesafb support.
> It installs /usr/share/v86d/initramfs and when you configure your
> kernel, you set CONFIG_INITRAMFS_SOURCE="/usr/share/v86d/initramfs" in
> order to have in included in your kernel image.

Will this be set somewhere globally to the initramfs automatically?
And doesn't this mean that a new kernel will need to be build just to satisfy 
this?

I'm trying to think of how best to avoid users who are not aware to get caught 
with non-booting systems.

Wouldn't automatic inclusion into grub.conf be a better approach? Not sure if 
grub.conf can handle a "global" setting for initramfs.

> > Also, how will
> > we be able to deal with situations where this script fails?
> 
> It should drop you to a minimal shell.

But, with udev then failing, will there be the /dev-entries to mount the 
different partitions to fix the environment?

> > If Gentoo does decide to follow the initramfs-route, why not simply
> > implement /etc/init.d/localmount in the initramfs?
> 
> I think that's pretty close to what we have planned, since the plan is
> to have the initramfs mount configuration stored on the root filesystem.

But still require a seperate configuration file for this?

> > Why require users to figure out which
> > filesystems are needed for udev?
> 
> Simply mount all filesystems containing files managed by the package
> manager with the initramfs. Anything else would expose you to the
> possibility of unsatisfied dependencies.

On my desktop, that would mean the following list:
/usr/
/var/
/opt/
/tmp/
/opt/tmp/

> > Also, I was actually hoping for a reply to the rest of my email as well,
> > especially the idea for splitting udev into 2 seperate processes.
> 
> In essence, what your doing here is playing a game of "let's see how
> long we can delay the mounting of essential filesystems". If you play
> this game, then again, you expose yourself to the possibility of
> unsatisfied dependencies. Therefore, the only foolproof approach is to
> mount all essential filesystems as soon as possible (via initramfs).

True, but I don't have any scripts configured for udev on my desktop.
My server has some scripts related to Xen, and those are all under 
/etc/xen/...

In this case, would it still be necessary to use an initramfs?

> > If someone can explain to me why my idea won't work, please let me know.
> 
> If your goal is to expose yourself to the possibility of unsatisfied
> dependencies, they your idea will achieve it.

No, my goal is to come up with a different solution to this problem which, on 
my system and possibly also on a lot of other systems, doesn't actually exist.

--
Joost