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Debian Installer: Stretch RC 2 released

Debian Installer: Stretch RC 2


Since the previous blog post, two Debian Installer release candidates were published, so both will be mentioned in this blog post.

Stretch RC 1

As mentioned in the Plans section of the Stretch Alpha 8 summary: with the full freeze coming up, it made sense to switch from the Alpha numbering to the Release Candidate one. That’s why Cyril published the Debian Installer Stretch RC 1 release on 2017-01-15.

Unfortunately, some blockers were found with merged-/usr setups, so the new debootstrap default was reverted. Even if some of these bugs were fixed in the meanwhile, it seemed unreasonable to enable the new code again near the end of the stretch release cycle, so it’s going to be postponed until after the buster release cycle has started.

Here is a list of other changes:

Stretch RC 2

Since the Linux kernel team was finally moving towards the target kernel version for Stretch (4.9, even if earlier discussions mentioned 4.10), it seemed like a good idea to get a new Debian Installer released as soon as possible, which explains why Debian Installer Stretch RC 2 was released on 2017-02-02, only a few weeks after Stretch RC 1.

Another significant change happened besides the Linux kernel update, with the os-prober component receiving major changes. Let’s have a look at its description:

    Package: os-prober
    Description: utility to detect other OSes on a set of drives
     This package detects other OSes available on a system and outputs the
     results in a generic machine-readable format.

This component is used to determine which other operating systems might be hanging around on various partitions and discs, and it’s used e.g. by update-grub to include menu entries for other Linux distributions, Windows, etc. Unfortunately, its historical operating system detection code has been triggering issues in some environments involving virtualization, which ended up in data loss in some cases.

The relevant code was heavily overhauled, and one might hit some regressions with new versions of this component (1.72 and later). Details about these significant changes can be found in the changelog entry for the 1.72 upload, and one might notice that the preparations for this new release candidate resulted in a last-minute regression fix in the 1.74 upload. Similar issues have been reported with the dmsetup create command hanging, leading to a frozen progress indicator when grub is being set up (see bug report #853927). This can be worked around by switching to a console and killing the dmsetup process (see this message for more details), until this issue is fully diagnosed and fixed.

Next release candidate

With the full freeze in effect, Debamax is trying to make sure Cyril can spend as much time as possible on two complementary tasks:

More to come in our next Debian Installer report!

Published: Mon, 13 Feb 2017 13:30:00 +0100

Debian Installer: Stretch Alpha 8 released

Debian Installer: Stretch Alpha 8

Release process

It took a few months after Stretch Alpha 7 (published 2016-07-04), but the Stretch Alpha 8 release of the Debian Installer happened a few days ago. Release preparations had to be delayed a bit because a fix was needed in the linux packaging (see bug report #839552) so that mounting FAT partitions worked again, since this is needed for EFI support.

As a release manager, Cyril has to make sure things look good enough for a release. This usually involves freezing udeb-producing packages for a while, so that the main set of packages used to build the Debian Installer doesn’t get any last minute changes that might bring some regressions while stabilization is in progress.

The debian-installer package got uploaded on 2016-10-27 but two major issues popped up:

The first issue was due to the rather recent linux/linux-signed split. The idea behind this move is preparing for Secure Boot support, with linux being used to build linux kernel and modules as usual, and linux-signed holding extra signatures for them, so that they can be verified cryptographically. This exposed an awful and old bug which hadn’t been detected until now. Then an extra commit got added as a work around for the linux/linux-signed specific situation: code comes from the linux source package, so that’s what needs to be listed in Built-Using. Further improvements are planned (see bug report #842719), by checking for a possible Built-Using field in each udeb, so that this workaround can be replaced by some more generic code.

The second issue was due to the reintroduction of InRelease support. There are two ways of validating the contents of a given distribution on a Debian mirror: checking the Release file against its detached signature (Release.gpg), or checking the InRelease file alone, as it contains an inline signature. Since only gpgv is available in a Debian Installer environment, the idea was to split the InRelease file into two files: the Release file and its signature. The tricky part is that the final newline is dropped by GnuPG, so a little tr … | sed … | tr … dance was added to do the same. Unfortunately, while it works fine with usual implementations of those commands, that’s not the case with the busybox implementation used in Debian Installer, leading to a bad signature result during the installation process (see bug report #842591). Thankfully Ansgar Burchardt had a proof of concept ready with a simple state machine in POSIX shell, which Cyril could merge and upload to fix debootstrap-udeb, fixing this showstopper.

Major update: debootstrap and merged-/usr

As mentioned above, debootstrap was updated, but not only for InRelease support. It received a number of fixes and improvements (see the release announce for the details), but the biggest change deserves a longer explanation: debootstrap now defaults to merged-/usr.

Once upon a time, UNIX systems were booted from a floppy disk, and once the boot sequence had finished, one would mount extra resources onto the /usr directory: programs, libraries, home directories, etc. Nowadays, it makes little sense to keep the distinction between boot-time and non-boot-time tools, and it was proposed to get rid of this distinction entirely. One way to achieve this is as simple as setting up symlinks for a number of directories: bin, sbin, lib, and other libXX (one can find lib32, lib64, etc. depending on the architecture), respectively pointing at usr/bin, usr/sbin, usr/lib, etc. This approach means there’s no need to change any single package, it’s just about using a specific directories+symlinks setup at installation time.

The options to enable or disable this feature are --merged-usr and --no-merged-usr respectively. The Debian script (shared across many versions) was updated to default to merged-/usr for stretch and later, which explains why this Debian Installer Stretch Alpha 8 release now defaults to a merged-/usr setup.

Credits: This change was driven by both Marco d’Itri and Ansgar Burchardt, while Julien Cristau worked on most other changes. Thanks!

Some final notes:

Next release: Stretch Alpha 9

A few things are planned for the next release:

Published: Tue, 22 Nov 2016 00:08:00 +0100

Hello, World!

Hello, World!

Debamax SAS has been successfully registered with the Trade and Company Register in Rennes, and has officially started operating in October! The legal notices page has further information regarding this registration and identification numbers.

A Twitter account (@DEBAMAX) is going to be set up to complement this website and its RSS feed.

Published: Wed, 7 Oct 2015 12:00:00 +0200