starlingx/kernel
Code Issues Proposed changes

kernel: Disable NVMe multi-path kconfig option

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This commit disables the NVMe multi-path kernel configuration option,
which was introduced with kernel v4.15-rc1, and is included in
StarlingX's v5.10-based kernel.

This feature exposes block devices such as "nvme0c0n1" in
/sys/class/block with the "hidden" attribute set to 1; however, the
older anaconda installer and user-space packages that StarlingX inherits
from CentOS 7 were not programmed to ignore such hidden block devices.
This results in anaconda reporting an error when probing the disks on
the system and aborting the installation. Similarly, the "lsblk" program
reports warnings about unrecognized block devices.

Both of these issues were fixed upstream with the following commits:
- 8957eb1f82
- https://git.kernel.org/pub/scm/utils/util-linux/util-linux.git/commit/?id=c8487d854ba5cf5bfcae78d8e5af5587e7622351

Given the difficulty of auditing all of CentOS 7's user-space for
potential incompatibilities with NVMe multi-path support, this commit
disables this feature.

The following options were considered to disable this option:
- Unset CONFIG_NVME_MULTIPATH (implemented in this commit)
- Use the kernel command line argument nvme_core.multipath=0
- Use a modprobe.d configuration file with the following contents:
  "options nvme_core multipath=0".

Of these options, the first was chosen to ensure non-error-prone
consistency across all StarlingX configurations, even though the latter
two options are more flexible.

Verification
- The issue was confirmed to exist on a standalone server with NVMe
  multi-path support, by attempting to install StarlingX using an ISO
  image built from StarlingX's master branch, in All-in-One simplex
  mode.
- An ISO image was successfully built with this commit using a
  monolithic incremental build procedure.
- The built ISO image was used to install StarlingX succcessfully onto
  the same standalone server in All-in-One simplex mode.
- Basic disk operations were carried out by creating a partition and a
  file system on the NVMe drive, as well as using dd in a loop to write
  zero bytes to a file created in the same file system.

  (Note that the same test procedure was not repeated with a server that
  has unaffected NVMe controllers due to lab availability constraints.
  Inspection of the kernel's NVMe multi-path support code indicates that
  the kernel falls back to non-multi-path code paths when an NVMe
  controller does not support this feature.)

Closes-Bug: 1967190
Change-Id: I791cfb6d7bc141e2114dea5e7f8d648b6df81f14
Signed-off-by: M. Vefa Bicakci <vefa.bicakci@windriver.com>
This commit is contained in:
M. Vefa Bicakci 2022-03-30 13:39:01 -04:00
parent 84d7517d11
commit 6fe8d60832
2 changed files with 4 additions and 0 deletions
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2
kernel-rt/files/kernel-x86_64-rt.config.tis_extra
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@ -1091,3 +1091,5 @@ CONFIG_GVE=m
# CONFIG_FRAMEBUFFER_CONSOLE_LEGACY_ACCELERATION is not set # CONFIG_FRAMEBUFFER_CONSOLE_LEGACY_ACCELERATION is not set
# CONFIG_BNXT is not set # CONFIG_BNXT is not set
# CONFIG_NVME_MULTIPATH is not set

2
kernel-std/files/kernel-x86_64.config.tis_extra
View File

@ -1599,3 +1599,5 @@ CONFIG_PCI_REALLOC_ENABLE_AUTO=y
# CONFIG_FRAMEBUFFER_CONSOLE_LEGACY_ACCELERATION is not set # CONFIG_FRAMEBUFFER_CONSOLE_LEGACY_ACCELERATION is not set
# CONFIG_BNXT is not set # CONFIG_BNXT is not set
# CONFIG_NVME_MULTIPATH is not set