The simplest unit of kernel Metadata is the configuration-only
feature.
This feature consists of one or more Linux kernel configuration
parameters in a configuration fragment file
(.cfg
) and a .scc
file
that describes the fragment.
The Symmetric Multi-Processing (SMP) fragment included in the
linux-yocto-3.19
Git repository
consists of the following two files:
cfg/smp.scc: define KFEATURE_DESCRIPTION "Enable SMP" define KFEATURE_COMPATIBILITY all kconf hardware smp.cfg cfg/smp.cfg: CONFIG_SMP=y CONFIG_SCHED_SMT=y # Increase default NR_CPUS from 8 to 64 so that platform with # more than 8 processors can be all activated at boot time CONFIG_NR_CPUS=64
You can find information on configuration fragment files in the "Creating Configuration Fragments" section of the Yocto Project Development Manual and in the "Generating Configuration Files" section earlier in this manual.
KFEATURE_DESCRIPTION
provides a short description of the fragment.
Higher level kernel tools use this description.
The kconf
command is used to include the
actual configuration fragment in an .scc
file, and the "hardware" keyword identifies the fragment as
being hardware enabling, as opposed to general policy,
which would use the "non-hardware" keyword.
The distinction is made for the benefit of the configuration
validation tools, which warn you if a hardware fragment
overrides a policy set by a non-hardware fragment.
kconf
statements, one per fragment.
As described in the "Generating Configuration Files" section, you can use the following BitBake command to audit your configuration:
$ bitbake linux-yocto -c kernel_configcheck -f