[Bug 1771557] Re: NVMe boot drives not supported - failing in generating initramfs

[Guilherme G. Piccoli]

** Description changed:

- [Impact] 
- The initramfs-tools hook-functions script cannot translate nvmeXnYpZ to nvmeXnY block device, so it's failing and not building the initram disk.
+ [Impact]
  
- Upstream solution is composed for at least 2 patches (it's a series, but
+ 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 at decadent.org.uk>
  hook-functions: Rewrite block device sysfs lookup to be generic
  
  commit 8ac52dc0
  Author: Ben Hutchings <ben at decadent.org.uk>
  hook-functions: Include modules for all components of a multi-disk device
  
- Instead of doing the backport, which is huge, 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 SRU to Trusty only.
+ 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]
- To be added.
+ 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 /
+ )
  
  
- [Regression Potential] 
- If the sed expression was somewhat broken, we could have an issue generating initiramfs for generic block devices, like regular HDDs.
+ 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

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https://bugs.launchpad.net/bugs/1771557

Title:
  NVMe boot drives not supported - failing in generating initramfs

Status in initramfs-tools:
  Fix Released
Status in initramfs-tools package in Ubuntu:
  Fix Released
Status in initramfs-tools source package in Trusty:
  In Progress
Status in initramfs-tools source package in Xenial:
  Fix Released

Bug description:
  [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 at decadent.org.uk>
  hook-functions: Rewrite block device sysfs lookup to be generic

  commit 8ac52dc0
  Author: Ben Hutchings <ben at decadent.org.uk>
  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

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