Architecture-Specific Code
^^^^^^^^^^^^^^^^^^^^^^^^^^
The file include/nuttx/arch.h identifies all of the APIs that must
be provided by the architecture specific logic. (It also includes
arch/<arch-name>/arch.h as described below).
Directory Structure
^^^^^^^^^^^^^^^^^^^
Thie arch directory contains architecture specific logic. Each aructure
provide a a subdirectory <arch-name>under arch/ with the folling characteristics:
<arch-name>
|-- Make.defs
|-- defconfig
|-- setenv.sh
|-- include
| |-- arch.h
| |-- irq.h
| `-- types.h
`-- src
|-- Makefile
`-- (architecture-specific source files)
Summary of Files
^^^^^^^^^^^^^^^^
Make.defs -- This makefile fragment provides architecture and
tool-specific build options. It will be included by all other
makefiles in the build (once it is installed). This make fragment
should define:
Tools: CC, LD, AR, NM, OBJCOPY, OBJDUMP
Tool options: CFLAGS, LDFLAGS
When this makefile fragment runs, it will be passed TOPDIR which
is the path to the root directory of the build. This makefile
fragment may include ${TOPDIR}/.config to perform configuration
specific settings. For example, the CFLAGS will most likely be
different if CONFIG_DEBUG=y.
defconfig -- This is a configuration file similar to the Linux
configuration file. In contains varialble/value pairs like:
CONFIG_VARIABLE=value
This configuration file will be used at build time:
(1) as a makefile fragment included in other makefiles, and
(2) to generate include/nuttx/config.h which is included by
most C files in the system.
The following variables are recognized by the build (you may
also include architecture-specific settings).
Architecture selection:
CONFIG_ARCH - identifies the arch subdirectory
CONFIG_ARCH_name - for use in C code
General OS setup
CONFIG_EXAMPLE - identifies the subdirectgory in examples
that will be used in the build
CONFIG_DEBUG - enables built-in debug options
CONFIG_DEBUG_VERBOSE - enables verbose debug output
CONFIG_HAVE_LOWPUTC - architecture supports low-level, boot
time console output
CONFIG_RR_INTERVAL - The round robin timeslice will be set
this number of milliseconds; Round robin scheduling can
be disabled by setting this value to zero.
CONFIG_SCHED_INSTRUMENTATION - enables instrumentation in
scheduler to monitor system performance
CONFIG_TASK_NAME_SIZE - Spcifies that maximum size of a
task name to save in the TCB. Useful if scheduler
instrumentation is selected. Set to zero to disable.
CONFIG_START_YEAR, CONFIG_START_MONTH, CONFIG_START_DAY -
Used to initialize the internal time logic.
CONFIG_JULIAN_TIME - Enables Julian time conversions
CONFIG_DEV_CONSOLE - Set if architecture-specific logic
provides /dev/console. Enables stdout, stderr, stdin.
Allow for artchitecture optimized implementations
The architecture can provide optimized versions of the
following to improve sysem performance
CONFIG_ARCH_MEMCPY, CONFIG_ARCH_MEMCMP, CONFIG_ARCH_MEMMOVE
CONFIG_ARCH_MEMSET, CONFIG_ARCH_STRCMP, CONFIG_ARCH_STRCPY
CONFIG_ARCH_STRNCPY, CONFIG_ARCH_STRLEN, CONFIG_ARCH_BZERO
CONFIG_ARCH_KMALLOC, CONFIG_ARCH_KZMALLOC, CONFIG_ARCH_KFREE
Sizes of configurable things (0 disables)
CONFIG_NPTHREAD_KEYS - The number of items of thread-
specific data that can be retained
CONFIG_NFILE_DESCRIPTORS - The maximum number of file
descriptors (one for each open)
CONFIG_NFILE_STREAMS - The maximum number of streams that
can be fopen'ed
CONFIG_STDIO_BUFFER_SIZE - Size of the buffer to allocate
on fopen. (Only if CONFIG_NFILE_STREAMS > 0)
CONFIG_NUNGET_CHARS - Number of characters that can be
buffered by ungetc() (Only if CONFIG_NFILE_STREAMS > 0)
CONFIG_PREALLOC_MQ_MSGS - The number of pre-allocated message
structures. The system manages a pool of preallocated
message structures to minimize dynamic allocations
CONFIG_MQ_MAXMSGSIZE - Message structures are allocated with
a fixed payload size given by this settin (does not include
other message structure overhead.
CONFIG_PREALLOC_WDOGS - The number of pre-allocated watchdog
structures. The system manages a pool of preallocated
watchdog structures to minimize dynamic allocations
Stack and heap information
CONFIG_BOOT_FROM_FLASH - Some configurations support XIP
operation from FLASH.
CONFIG_STACK_POINTER - The initial stack pointer
CONFIG_PROC_STACK_SIZE - The size of the initial stack
CONFIG_PTHREAD_STACK_MIN - Minimum pthread stack size
CONFIG_PTHREAD_STACK_DEFAULT - Default pthread stack size
CONFIG_HEAP_BASE - The beginning of the heap
CONFIG_HEAP_SIZE - The size of the heap
setenv.sh -- This is a script that you can include that will be installed at
the toplevel of the directory structure and can be sourced to set any
necessary environment variables.
include/arch.h
This is a hook for any architecture specific definitions that may
be needed by the system. It is included by include/nuttx/arch.h
include/types.h
This provides architecture/toolchain-specific definitions for
standard types. This file should typedef:
sbyte, ubyte, uint8, boolean, sint16, uint16, sint32, uint32
and
sint64, uint64
if the architecture supports 64-bit integers.
irqstate_t
Must be defined to the be the size required to hold the interrupt
enable/disable state.
This file will be included by include/sys/types.h and be made
available to all files.
include/irq.h
This file needs to define some architecture specific functions (usually
inline if the compiler supports inlining) and structure. These include:
- struct xcptcontext. This structures represents the saved context
of a thread.
- irqstate_t irqsave(void) -- Used to disable all interrupts.
- void irqrestore(irqstate_t flags) -- Used to restore interrupt
enables to the same state as before irqsave was called.
This file must also define NR_IRQS, the total number of IRQs supported
by the board.
src/Makefile
This makefile will be executed to build the targets src/libup.a and
src/up_head.o. The up_head.o file holds the entry point into the system
(power-on reset entry point, for example). It will be used in
the final link with libup.a and other system archives to generate the
final executable.
Configuring NuttX
^^^^^^^^^^^^^^^^^
Configuring NuttX requires only copying
arch/<arch-name>/Make.def to ${TOPDIR}/Make.defs
arch/<arch-name>/setenv.sh to ${TOPDIR}/setenv.sh
arch/<arch-name>/defconfig to ${TOPDIR}/.config
There is a script that automates these steps. The following steps will
accomplish the same configuration:
cd tools
./configure.sh <arch-name>
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