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You have been subscribed to a public bug by Guilherme G. Piccoli (gpiccoli):

[Impact]

When creating the initramfs image, mkinitramfs has multiple options on
how to include modules. The default (and most common) one is the
"MODULES=most", which includes the majority of filesystem modules and
all the block device drivers. One other option is "MODULES=dep", which
tries to descend in the sysfs hierarchy and guess modules to add, with
the goal of reduce the size of initramfs.

For the MODULES=dep case, the initramfs-tools hook-functions script
cannot translate nvmeXnYpZ to nvmeXnY block device, so it's failing in
the sysfs lookup, so it does not build the initram disk.

Upstream solution is composed of at least 2 patches (it's a series, but
the 2 below are really the needed ones):

commit 3cb744c9
Author: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
hook-functions: Rewrite block device sysfs lookup to be generic

commit 8ac52dc0
Author: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
hook-functions: Include modules for all components of a multi-disk device

Instead of doing the huge backport, we added another sed substitution: currently the script has substitutions for sdX and hdX, in order to convert sda1 to sda, for example. The new substitution converts nvmeXnYpZ to nvmeXnY.
It's less intrusive than the full backport, since this is a minimal SRU to Trusty only.


[Test Case]
1. Install Trusty with rootfs in a multi-disk(md) array composed of two nvme partitions - in my tests, I've used a RAID1.

(lsblk output of my test env:

nvme0n1     259:0    0    10G  0 disk  
└─nvme0n1p1 259:1    0    10G  0 part  
  └─md0       9:0    0    10G  0 raid1 /
nvme1n1     259:2    0    10G  0 disk  
└─nvme1n1p1 259:3    0    10G  0 part  
  └─md0       9:0    0    10G  0 raid1 /
)


2. Once system is booted, modify the "/etc/initramfs-tools/initramfs.conf", replacing "MODULES=most" to "MODULES=dep".

3. Update your initramfs by running something like:
"update-initramfs -u -k <your kernel version>"

The initramfs creating procedure will fail, unless the patch from this
LP is present.


[Regression Potential]
If the sed expression was somewhat broken, we could have an issue generating initiramfs when MODULES is set to "dep", even for generic block devices (like regular HDDs).


[Other Info]
This issue is based on Debian bug #785147: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=785147

** Affects: initramfs-tools
     Importance: Unknown
         Status: Fix Released

** Affects: initramfs-tools (Ubuntu)
     Importance: Medium
     Assignee: Guilherme G. Piccoli (gpiccoli)
         Status: Fix Released

** Affects: initramfs-tools (Ubuntu Trusty)
     Importance: High
     Assignee: Guilherme G. Piccoli (gpiccoli)
         Status: In Progress

** Affects: initramfs-tools (Ubuntu Xenial)
     Importance: Medium
         Status: Fix Released


** Tags: sts trusty
-- 
NVMe boot drives not supported - failing in generating initramfs
https://bugs.launchpad.net/bugs/1771557
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