Possibilities for Emdebian Crush

Crush 2.0 was abandoned last year when the freeze for Debian Squeeze was still scheduled to start at the end of 2009. Even with the expected delays in the timetable for the Debian release, there never was going to be enough time to get Crush 2.0 released with the resources available. Subsequent Crush releases have always been planned, only the release of Crush 2.0 alongside Debian 6.0 (Squeeze) was abandoned.

However, Emdebian Grip has developed nicely and Grip 2.0 is going to be a significant advance over Grip 1.0 - lots more packages, lots of bugs fixed for smoother installations, multistrap support, etc.

The success of Grip has led to a slim chance of working out something for Emdebian Crush. The current state of cross-building / multiarch in Debian means that cross-building more than a handful of packages is simply unrealistic with the resources available within Emdebian. Instead, Crush will be based on Grip for 2.0 and subsequent releases, until things settle out.

Packages that are in Grip and which are designed upstream for embedded situations will simply be made accessible in Crush without further changes. Cross-building packages like this results in binaries that are all but identical to the Grip equivalent. (There is a massive difference between adapting a package for Crush and designing the package from scratch for embedded use. Emdebian is not taking on that task.)

The changes that Crush will make are being calculated, using a shortlist of packages that are (typically) not designed for embedded use but which support a long, long string of --enable-foo options in the build system - most of which Crush can change into --disable-foo. This results in fewer dependencies for the resulting binary packages so that things like LDAP can be removed. The packages themselves are being selected on the basis of what was released in Crush 1.0 for compatibility reasons. The source packages and the resulting binary packages will be renamed (busybox-crush etc.) and suitable Provides: Replaces: and Conflicts: deployed, allowing mixing of Grip and Crush packages on one device.

Other changes are then based around replacing coreutils with a reconfigured busybox and removing perl completely. Wrapper scripts, helpers and other changes will try to stitch the gaps.

It's a chance, a bit slim but a chance nonetheless. The plan offers a possibility, a worthwhile experiment. If it works, Emdebian Crush 2.0 could be a reality on seven architectures and with 2,000 packages available, released alongside Debian 6.0 (Squeeze). If it fails, people will just have to wait for multiarch to settle out and Crush 3.0, due for release alongside Debian 7.0 (Squeeze+1). In the meantime, there's always Emdebian Grip.