compartmentalisation.txt
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PART-SPECIFIC SOURCE COMPARTMENTALISATION
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The sources for various parts are compartmentalised at two different levels:
(1) Processor level
The "processor level" is a CPU core plus the other on-silicon
peripherals.
Processor-specific header files are divided among directories in a similar
way to the CPU level:
(*) include/asm-mn10300/proc-mn103e010/
Support for the AM33v2 CPU core.
The appropriate processor is selected by a CONFIG_MN10300_PROC_YYYY option
from the "Processor support" choice menu in the arch/mn10300/Kconfig file.
(2) Unit level
The "unit level" is a processor plus all the external peripherals
controlled by that processor.
Unit-specific header files are divided among directories in a similar way
to the CPU level; not only that, but specific sources may also be
segregated into separate directories under the arch directory:
(*) include/asm-mn10300/unit-asb2303/
(*) arch/mn10300/unit-asb2303/
Support for the ASB2303 board with an ASB2308 daughter board.
(*) include/asm-mn10300/unit-asb2305/
(*) arch/mn10300/unit-asb2305/
Support for the ASB2305 board.
The appropriate processor is selected by a CONFIG_MN10300_UNIT_ZZZZ option
from the "Unit type" choice menu in the arch/mn10300/Kconfig file.
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COMPILE TIME
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When the kernel is compiled, symbolic links will be made in the asm header file
directory for this arch:
include/asm-mn10300/proc => include/asm-mn10300/proc-YYYY/
include/asm-mn10300/unit => include/asm-mn10300/unit-ZZZZ/
So that the header files contained in those directories can be accessed without
lots of #ifdef-age.
The appropriate arch/mn10300/unit-ZZZZ directory will also be entered by the
compilation process; all other unit-specific directories will be ignored.