Re: [gentoo-dev] rfc: using /libexec

[Robin H. Johnson]

On Wed, Sep 07, 2011 at 08:35:46PM -0400, Rich Freeman wrote:
> On Wed, Sep 7, 2011 at 5:31 PM, Joshua Kinard <kumba@g.o> wrote:
> > Never once have I had any issues
> > with separate / and /usr, and none of them use an initramfs.
> Ditto here, but that doesn't mean that problems don't exist.  Right now the
> problems are likely to be subtle, perhaps arising only with certain
> combinations of hardware/etc.  Maybe if you had a bluetooth keyboard or
> something it might not work, or maybe if /usr were mounted on a bluetooth
> hard drive or something (do they even make those?).
Bluetooth keyboard wanted during early boot (to put in the root password
for a fsck repair after a hard shutdown) is one that bit me already.

> > As far as initramfs, is this something that would need to go into the
> > kernel?
> Well, the kernel comes with code for making an initramfs, but most likely it
> would be implemented in a separate package.  The initramfs isn't part of the
> kernel - it is loaded by grub at boot time and its address is passed to the
> kernel.  So, the file needs to be on /boot.
That's not always true, see further down.

> I also netboot some of my systems, and they have limits on the total
> > size of the kernel image (7.2MB on one, ~40MB on another, etc), hence the
> > need to keep this small or find another way to do things.
> I think that pxelinux supports initramfs - I know it supports initrd at
> least and I don't think it makes any difference at the bootloader level.  In
> fact, things like network booting are one of the drivers behind the Fedora
> project to have dracut mount /usr.  Their plan is to just move everything
> into /usr, allow it to be NFS-mounted, and then with one mountpoint
> everything the system needs is available.  Eventually in Fedora /lib and
> /bin will just be symlinks into /usr.  That will work fine as long as dracut
> mounts /usr.
That's not quite as easy for Kumba... Some of the MIPS bootloaders are
very limited. At least one of them requires that the initramfs be built
INTO the kernel.

>
> Are there possibilities about breaking off just a small piece of openrc and
> > putting that into /run (or /boot)?  Enough of the core scripts so that it
> > can find /usr and mount it before continuing?
> Well, it certainly could be done, but it doesn't seem to be the direction
> anybody else is going.  Instead the plan is to just create a very minimal
> initramfs that gets the job done.
That's pretty much the only stuff in WilliamH's prototype. Just enough
to get /usr mounted (/run comes for almost free at that point basically,
it's just mounting tmpfs on /newroot/run/).

-- 
Robin Hugh Johnson
Gentoo Linux: Developer, Trustee & Infrastructure Lead
E-Mail     : robbat2@g.o
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