NovellKernelModulePackages

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1 SUSE Kernel Module Packages

SUSE Kernel Module Packages

Novell provide support for Kernel Module Packages in their CODE10 releases (SLES10 and OpenSuSE 10.1), and in a precursory version in SLES9. The following information is based upon material at http://en.opensuse.org/Kernel_Module_Packages and discussion with Andreas Gruenbacher (agruen@suse.de) and other SuSE community members about their KMP work. Empirical testing has also taken place.

Note: To test this out, you'll need to have an up-to-date installation of OpenSuSE (or SLES10). It is recommended that you use the "Factory" development Distribution - http://en.opensuse.org/Factory.

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Overview

Novell KMPs rely upon two key pieces of information:

Symbolic reference data for the current kernel in /boot/sym*
RPM "provides" and "requires" dependencies referencing these.

The internal build process is somewhat complex, but the end goal is to provide RPM packages with dependencies against a set of symbol exports that are provided dependencies of a kernel package. Thus, it's possible for automated resolution to occur[0].

For example, the "ivtv" kernel (ivtv-kmp-default) module might include the following RPM dependencies:

Provides:
- ivtv-kmp = 0.7.0_2.6.16.12_3
- ksym(ivtv_api) = 3370d1f8
- ksym(ivtv_cards) = 86757ef5
- ksym(ivtv_cards_active) = 70196ffb
- ksym(ivtv_clear_irq_mask) = 65dce529
- ksym(ivtv_debug) = 14f67530
- ksym(ivtv_reset_ir_gpio) = c20c986f
- ksym(ivtv_set_irq_mask) = b26f3794
- ksym(ivtv_vapi) = 8737f753
- ivtv-kmp-default = 0.7.0_2.6.16.12_3-12

Requires:
- rpmlib(VersionedDependencies) <= 3.0.3-1
- kernel-default
- /bin/sh
- /bin/sh
- /bin/sh
- rpmlib(PayloadFilesHavePrefix) <= 4.0-1
- rpmlib(CompressedFileNames) <= 3.0.4-1
- kernel(drivers) = 0fe6383185b77d3c
- kernel(drivers_pci) = f982906dcfcc9ba3
- kernel(mm) = 3d6b445a058e7d3f
- kernel(drivers_media_video) = c5f862783e632d21
- kernel(kernel) = 3e632392437173c4
- kernel(vmlinux) = 73b8cba1c47dd165
- kernel(kernel_irq) = dd1d73732d05a591
- kernel(arch_i386_kernel) = 74a0933fa6e553b6
- kernel(arch_i386_kernel_cpu) = 7e943412451173b6
- kernel(arch_i386_kernel_cpu_mtrr) = badf815515a4fe72
- kernel(drivers_base) = 0d991d69743e5e95
- kernel(arch_i386_mm) = d424f52befea78dc
- kernel(drivers_i2c) = 60530549d9f89642
- kernel(drivers_video) = d22ead68a52a9411
- rpmlib(PayloadIsBzip2) <= 3.0.5-1

The kernel() and ksym() dependencies encapsulate the versions of kernel symbols. Since RPM doesn't well handle 8000+ dependencies, these are grouped into a version per directory (for example) of the kernel source - e.g. arch_i386_kernel for arch/i386/kernel. KMPs are installed by default into the usual /lib/modules location, except that they are located under "updates" - "weak-updates" are created for kernels that meet kABI requirements but aren't of the same verison.

Kernels and Kernel Module Packages employ the weak-modules script (from module-init-tools) in their %post and %postun scripts to create symlinks to compatible modules from other kernel versions: When installing a Kernel Module Package, the script creates weak-updates symlinks in all weak-updates directories of compatible kernels (unless such symlinks from more recent kernel versions exist already). During kernel upgrades, the script goes through all update modules in /lib/modules/*/updates of all other kernels, and symlinks compatible modules into the new kernel's /lib/modules/*/weak-updates directory. (If multiple compatible modules are available, those with the highest kernel release number win.)

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Novell KMP Example

Novell provide an example KMP in /usr/share/doc/packages/kernel-source/novell-kmp, along with a reference to the build instructions for building a SuSE kernel - see Documentation below.

The spec file begins in the normal fashion:

Name:         novell-example
BuildRequires: kernel-source kernel-syms
License:      GPL
Group:        System/Kernel
Summary:      Example Kernel Module Package
Version:      1.1
Release:      0
Source0:      %name-%version.tar.bz2
BuildRoot:    %{_tmppath}/%{name}-%{version}-build

Then comes the magic macro:

%suse_kernel_module_package kdump um

Then a description:

%description
This is an example Kernel Module Package.

Then we create a sub-package "template" for different kernel flavors which defines the summary, group, and description of the various sub-packages for the different kernel flavors:

%package KMP
Summary: Example Kernel Module
Group: System/Kernel

%description KMP
This is one of the sub-packages for a specific kernel. All the
sub-packages will share the same summary, group, and description.

The prep and build process is fairly standard for 2.6 kernel modules:

%prep
%setup
set -- *
mkdir source
mv "$@" source/
mkdir obj

%build
export EXTRA_CFLAGS='-DVERSION=\"%version\"'
for flavor in %flavors_to_build; do
    rm -rf obj/$flavor
    cp -r source obj/$flavor
    make -C /usr/src/linux-obj/%_target_cpu/$flavor modules \
        M=$PWD/obj/$flavor
done

%install
export INSTALL_MOD_PATH=$RPM_BUILD_ROOT
export INSTALL_MOD_DIR=updates
for flavor in %flavors_to_build; do
    make -C /usr/src/linux-obj/%_target_cpu/$flavor modules_install \
         M=$PWD/obj/$flavor
done

So, the real magic happens in the %suse_kernel_module_package macro. This RPM macro automatically determines the set of RPM dependencies that will be produced for this module.

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