kmod add zstd support

[Dimitri John Ledkov]

[Impact]

 * To safe diskspace, upcoming devel series / hwe kernels may turn on zstd kernel module compression. Kmod since impish support zstd support. But in order to keep hwe kernels at parity, or allow inspecting jammy modules from focal host, it would be beneficial for kmod in focal to support zstd compressed modules.

[Test Plan]

 * Pick any kernel module

 * Compress it with zstd: $ zstd *.ko

 * Check that modinfo can read it: $ modinfo *.ko.zst

[Where problems could occur]

 * kmod will gain a new dependecy on libzstd1, however it should already be present, because dpkg in focal depends on libzstd1 already.

 * initramfs-tools already supports compressed modules, but in focal at the moment it does so in an inefficient manner (regresses bootspeed), this has been improved in https://launchpad.net/ubuntu/+source/initramfs-tools/0.140ubuntu8 and is yet to be SRUed into Focal.

[Launchpad Janitor (janitor)]

This bug was fixed in the package kmod - 28-1ubuntu4

---------------
kmod (28-1ubuntu4) impish; urgency=medium

  * Enable testsuite during build.

kmod (28-1ubuntu3) impish; urgency=medium

  * Build with zstd compression enabled. LP: #1933491

 -- Dimitri John Ledkov <email address hidden> Thu, 24 Jun 2021 13:42:47 +0100

[Łukasz Zemczak (sil2100)]

Quick question from IRC here, for tracking:

17:38 < sil2100> xnox: hey, reviewing the kmod SRU for zstd - I have a question re: the debian/rules change of the added --disable-test-modules
17:38 < sil2100> What effect does it have? Why is that needed?

[Dimitri John Ledkov (xnox)]

@sil2100

--disable-test-modules \

 override_dh_auto_test:
+ dh_auto_test --builddir=build-deb

are needed together to enable building and running unittests during build.

Note previously focal builds did not run unittests at all.

The autoconf help text for the option says "disable building test modules during make check: cached modules will be used". What it means use the prebuilt kernel modules from the orig tarball for unittests, which works in launchpad builders. Without this option an attempt is made to rebuild test modules for the currently running kernel which is not possible or useful in launchpad. Installing linux-generic-headers and forcing the build for the current kernel in a given series is another alternative, but also not too sure if that is useful given prebuilt known/working modules for unittests are available.

[Brian Murray (brian-murray)]

Hello Dimitri, or anyone else affected,

Accepted kmod into focal-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/kmod/27-1ubuntu2.1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, what testing has been performed on the package and change the tag from verification-needed-focal to verification-done-focal. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-focal. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

[Ubuntu SRU Bot (ubuntu-sru-bot)]

All autopkgtests for the newly accepted kmod (27-1ubuntu2.1) for focal have finished running.
The following regressions have been reported in tests triggered by the package:

linux-aws-5.11/5.11.0-1028.31~20.04.1 (amd64)
linux-aws-5.8/5.8.0-1042.44~20.04.1 (amd64)
initramfs-tools/0.136ubuntu6.6 (amd64)
linux-azure-5.8/5.8.0-1043.46~20.04.1 (amd64)
linux-gcp-5.8/5.8.0-1039.41 (amd64)

Please visit the excuses page listed below and investigate the failures, proceeding afterwards as per the StableReleaseUpdates policy regarding autopkgtest regressions [1].

https://people.canonical.com/~ubuntu-archive/proposed-migration/focal/update_excuses.html#kmod

[1] https://wiki.ubuntu.com/StableReleaseUpdates#Autopkgtest_Regressions

Thank you!

[Dimitri John Ledkov (xnox)]

initramfs-tools ADT test passed on retry.

the kernel tests mentioned above are now for EOL kernels that have since all rolled to 5.13.

[Dimitri John Ledkov (xnox)]

# dpkg-query -W kmod
kmod 27-1ubuntu2

# modinfo ./zstd.ko.zst
modinfo: ERROR: Module alias ./zstd.ko.zst not found.

upgraded to new kmod:

# dpkg-query -W kmod
kmod 27-1ubuntu2.1

# modinfo ./zstd.ko.zst
filename: /lib/modules/5.4.0-109-generic/kernel/crypto/./zstd.ko.zst
alias: crypto-zstd
alias: zstd
description: Zstd Compression Algorithm
license: GPL
srcversion: C007A20DBED7E012AF5A0A8
depends: zstd_compress
retpoline: Y
intree: Y
name: zstd
vermagic: 5.4.0-109-generic SMP mod_unload modversions
sig_id: PKCS#7
signer: Build time autogenerated kernel key
sig_key: 2E:88:51:F0:25:CE:CD:BB:F2:FC:76:4E:F5:71:F2:A4:3F:3E:DC:F3
sig_hashalgo: sha512
signature: 62:91:50:E8:5F:FA:96:05:E8:CA:F4:9F:03:0A:5A:56:04:02:37:2D:
  06:56:A8:A7:40:02:95:61:78:5F:F3:73:8B:EB:EA:FB:62:F6:B1:B7:
  68:4F:A7:87:88:44:E1:85:41:C9:ED:BB:CD:34:02:A1:3E:7A:9A:E8:
  D8:24:84:94:64:D3:9F:FE:A7:3A:91:10:F3:90:B1:E7:71:25:26:BA:
  B8:CE:B8:59:E1:B9:DD:C0:0C:82:E3:9B:96:CF:E5:DB:BD:8F:77:11:
  87:E4:BB:BC:84:57:49:A3:D8:CE:D6:33:25:86:35:50:67:B5:0A:13:
  26:08:4D:66:E9:97:70:B5:F6:87:69:D2:89:EA:2A:40:38:30:88:AA:
  AD:ED:6C:0A:51:1E:62:E4:F1:13:47:8F:0B:AF:FB:53:A9:74:82:52:
  78:53:F2:8D:4D:DB:15:5C:76:4F:9A:77:C0:7F:6E:87:16:B3:DB:FD:
  C7:D6:C6:8E:14:D1:A6:F0:0B:03:4C:33:68:E8:75:29:93:E6:4F:AE:
  43:6D:90:4D:32:4B:A1:42:C1:AD:99:7C:C3:E2:B9:48:E6:F5:0D:DF:
  2F:09:C2:46:A6:98:55:47:16:92:EF:28:AB:41:9E:4D:E8:03:2C:21:
  AF:21:CD:13:1D:C5:A3:FE:03:99:12:03:88:9E:65:1A:82:85:2B:71:
  DD:EB:F8:7E:C3:B8:84:A1:AD:25:25:DC:FD:58:77:1A:CE:EA:F8:04:
  C2:E1:DF:AB:A1:17:00:26:96:E5:FA:3F:84:CC:98:ED:31:E2:A0:2F:
  E6:7D:20:13:D1:57:8C:AA:74:2D:04:7C:48:34:E0:7B:DF:3C:F6:66:
  4D:7A:E9:EF:5D:ED:66:7D:87:D6:98:2F:F7:92:3F:C7:CD:16:7B:D0:
  CE:B4:5B:A3:D9:9A:79:72:23:47:49:E0:69:B2:ED:44:E8:7F:7C:D6:
  12:BB:66:A7:5E:F6:0D:2C:9B:7B:DA:8E:76:A9:66:B1:71:44:12:30:
  83:DB:09:EE:4C:28:93:BD:50:51:E5:67:C3:B3:79:1C:27:86:82:02:
  21:B9:EB:59:54:99:A9:93:02:D3:32:F5:D0:43:05:62:ED:C6:E9:4B:
  F9:09:9D:40:A2:83:74:25:65:30:BF:59:3A:42:64:28:94:9C:34:79:
  42:59:81:22:CE:D0:80:56:A4:65:F8:A0:11:20:0F:A9:F2:F6:52:8C:
  D1:04:F6:D8:09:D0:D4:66:6E:21:12:AB:68:FD:34:1C:59:AF:9F:E9:
  AD:5C:A5:6F:AC:51:80:41:4C:62:28:A1:51:5B:C9:E0:C1:17:44:F1:
  A2:92:1E:39:00:07:96:E6:90:D9:CC:94

[Launchpad Janitor (janitor)]

This bug was fixed in the package kmod - 27-1ubuntu2.1

---------------
kmod (27-1ubuntu2.1) focal; urgency=medium

  * Build with zstd compression and testsuite enabled. LP: #1933491

 -- Dimitri John Ledkov <email address hidden> Fri, 28 Jan 2022 14:49:50 +0000

[Łukasz Zemczak (sil2100)]

The verification of the Stable Release Update for kmod has completed successfully and the package is now being released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.