+ Started by Linus Torvalds in 1991 as a kernel for i386
+ PCs: just a hobby, won't be big and professional like gnu
+
+
+ Adopted as the kernel of the Debian system in 1993
+
+
+ After 20 years' development, supports more hardware
+ architectures and devices than anything else
+
+
+ Hardware vendors must provide Linux drivers because
+ their customers demand it
+
+
+
+
+ Still the default kernel for the Debian system
+
+
-
Linux release model
+
Linux release model (1)
+
+ The old model:
+
+
+
+ Each stable release had even second component. Bug fixes and
+ minor features in stable releases with third component
+ incremented (e.g. 2.4.27)
+
+
+ Major development done separately, resulting in series of
+ unstable releases with odd second component (e.g. 2.5.50)
+
+
+ After a year or two, development resulted in a new stable
+ release
+
+
+ Problem: users waited years for new features, and then got many
+ more changes all at once. Particularly bad in the 2.4-2.6
+ transition.
+
+
-
Debian kernel team
+
Linux release model (2)
+
+ The new model:
+
+
+
+ Development results in a new stable(-ish) release every 2-3
+ months
+
+
+ git (and previously BitKeeper) made distributed development
+ and testing a lot easier
+
+
+
+
+ Each 2.6.x release has stable update branch; releases
+ numbered 2.6.x.y
+
+
+ Usually closed shortly after next stable release, but may
+ continue as a 'longterm' branch (e.g. 2.6.32.y)
+
+
+
+
+ Linux 3.0 doesn't change this, except that x is now
+ the second component and y is the third
+
+
-
Official Linux kernel packages
+
Debian kernel team (1)
+
+ Who are we?
+
+
+
+ Currently 5 general maintainers: Maximilian Attems, Bastian
+ Blank, dann frazier, Moritz Muehlenhoff and me
+
+
+ Many more specialised contributors:
+
+
Specific architectures
+
Specific features (e.g. Xen)
+
Bug triage
+
+
+
+ Would appreciate more help, particularly with bug triage and
+ PowerPC
+
+
-
Custom Linux kernel packages
+
Debian kernel team (2)
+
+ What do we do?
+
+
+
+ Bug triage - takes a huge amount of time
+
+
+ Backport bug fixes and features - particularly new hardware
+ support for stable
+
+
...while trying not to change kernel ABI in stable
+
+
+
+ Update build configurations for each new upstream release -
+ e.g. to enable new drivers
+
+
+ Try to ensure smooth upgrades when there are major
+ implementation changes - e.g. KMS, switch to libata drivers
+
+
+ Integrate some features not accepted upstream
+
+
+
+
+
+
Official Linux kernel packages (1)
+
+ Main source package is linux-2.6 (still!). Most binary package
+ names change regularly.
+
+
+
+ linux-image-upstream-abi-flavour
+ - compiled kernel and modules
+
+
+ linux-headers-upstream-abi-flavour
+ (and others) - development package for OOT modules
+
+
+ linux-libc-dev - headers for userland
+
+
+ linux-source-upstream - for custom kernels
+
+
+ linux-doc-upstream, linux-tools-upstream,
+ etc.
+
+
+ linux-support-upstream-abi - scripts and
+ metadata to support linux-latest-2.6
+
+
+
+
+
+
Official Linux kernel packages (2)
+
+ The linux-latest-2.6 source package builds meta-packages to
+ support automatic upgrades between binaries built from linux-2.6.
+
+
+
+ linux-image-flavour
+
+
+ linux-headers-flavour
+
+
+ linux-source, linux-doc, linux-tools, etc.
+
+
+
+ The installer will normally install linux-image-flavour
+ (for some appropriate flavour).
+
+
+
+
+
Official Linux kernel packages (3)
+
+
+ firmware-free - separate 'firmware' compliant with DFSG
+
+
+ linux-base - base package for images and tools
+
+
+ linux-kbuild-2.6 builds linux-kbuild-upstream -
+ code used for building OOT modules
+
+
+
+
+
+
Custom Linux kernel builds
+
+ The official packages work for most users, but not all:
+
+
+
+ Different ARM platforms need incompatible configurations,
+ and we cannot build them all
+
+
+ New features are not enabled immediately if we are worried
+ about potential regressions
+
+
+
+ Using either upstream source or Debian linux-source package:
+
+
+
+ make && make install
+
+
+ make deb-pkg - build packages
+
+
+ make-kpkg - build packages with more customisation;
+ requires kernel-package
+
+
Out-of-tree modules
+
+ The kernel team does not encourage the use of out-of-tree modules.
+ However, we support them by providing development packages and by
+ avoiding ABI changes during a stable release.
+
+
+ Debian has two packages to aid in building out-of-tree modules:
+
+
+
+ dkms - builds and installs modules automatically. Can
+ build packages for installation on other systems. Also
+ supported by Ubuntu and SUSE.
+
+
+ module-assistant - builds packages as directed.
+ Uses a separate package name for each kernel ABI.
+