Documentation/features: Explain kernel feature descriptions and add visualization script
The previous patches added arch support matrices for more than 40 generic kernel features
that need per architecture support.
The structure of the feature descriptions is the following:
Each feature has its own directory under Documentation/features/subsystem_name/feature_name/,
and the arch-support.txt file shows its current arch porting status.
For example, lockdep support is shown the following way:
triton:~/tip> cat Documentation/features/locking/lockdep/arch-support.txt
#
# Feature name: lockdep
# Kconfig: LOCKDEP_SUPPORT
# description: arch supports the runtime locking correctness debug facility
#
-----------------------
| arch |status|
-----------------------
| alpha: | TODO |
| arc: | ok |
| arm: | ok |
| arm64: | ok |
| avr32: | ok |
| blackfin: | ok |
| c6x: | TODO |
| cris: | TODO |
| frv: | TODO |
| h8300: | TODO |
| hexagon: | ok |
| ia64: | TODO |
| m32r: | TODO |
| m68k: | TODO |
| metag: | ok |
| microblaze: | ok |
| mips: | ok |
| mn10300: | TODO |
| nios2: | TODO |
| openrisc: | TODO |
| parisc: | TODO |
| powerpc: | ok |
| s390: | ok |
| score: | ok |
| sh: | ok |
| sparc: | ok |
| tile: | ok |
| um: | ok |
| unicore32: | ok |
| x86: | ok |
| xtensa: | ok |
-----------------------
For generic kernel features that need architecture support, the
arch-support.txt file in each feature directory shows the arch
support matrix, for all upstream Linux architectures.
The meaning of entries in the tables is:
| ok | # feature supported by the architecture
|TODO| # feature not yet supported by the architecture
| .. | # feature cannot be supported by the hardware
This directory structure can be used in the future to add other
files - such as porting guides, testing description, etc.
The Documentation/features/ hierarchy may also include generic
kernel features that works on every architecture, in that case
the arch-support.txt file will list every architecture as
supported.
To list an architecture's unsupported features, just do something
like: