On 11/17/2013 12:15 PM, Tanstaafl wrote:
On 2013-11-12 4:55 PM, Tanstaafl <tanstaafl@libertytrek.org> wrote:
Depending on your system, you might want to add one or more of the
following options:
Option     Description
--disklabel     Add support for LABEL= settings in your /etc/fstab
--dmraid     Add support for fake hardware RAID
--firmware     Add in firmware code found on the system
--gpg     Add in GnuPG support
--iscsi     Add support for iSCSI
--luks     Add support for luks encryption containers
--lvm     Add support for LVM
--mdadm     Add support for software RAID
--multipath     Add support for multiple I/O access towards a SAN
--zfs     Add support for ZFS

So, are these *all* of the potential options? If so, then I can probably
safely say that all I need is lvm...


these options say do additional tasks. i.e. initialise lvm volume groups or search and start all mdraid devices.  or all of the above.
you only need lvm if root/usr is on lvm.
you only need mdadm if root/usr is on a mdraid
if your root/usr is on a normal device  like /dev/sda3  but all data drives are on lvm then you still do not need these options.
they are just what to do in the initramfs to get root mounted.

Never got a response to this...

Maybe I can ask another way...

Is this a complete list of the items that may break BOOTING? I understand now that you can add pretty much any drivers that you want, but on my server (that has the separate /usr), modules are disabled and so I have every driver and filesystem built into the kernel.

Going just by the above list of items, the only thing I use is lvm, so I'm guessing (I *hate* guessing) that this is the only thing I need in my initramfs.

do you have kernel modules that are not compiled into the kernel in order to mount root ? 
i.e. is root on ext4 and ext4 is <M> in menuconfig
i.e. is root on an adaptec scsi card and the scsi drivers is  <M> in menuconfig
then you need  to edit genkernel's modules_load https://forums.gentoo.org/viewtopic-t-497370.html

for split /usr check out initramfs.mounts
http://sources.gentoo.org/cgi-bin/viewvc.cgi/gentoo-x86/sys-kernel/genkernel/files/initramfs.mounts?view=markup
i don't do this so can't comment if it works, maybe someone else can?
Another question - is there any reason I couldn't just enable everything just in case? Or could that cause other problems?

if you have them selected anyway, it jus tmakes the boot process slower as it scans for raid devices to find none..
On 2013-11-12 5:54 PM, Neil Bothwick <neil@digimed.co.uk> wrote:
> There is a very capable tool for examining your system and deciding
> what is needed... you.

Yes, but again, I have never had to worry about this - EVER - in the past. The question simply never came up.

Now, I am being FORCED to worry about it... and I want to understand it as much as possible.

hope this helps