翻译ecos 手册----HAL架构1

In order to write an eCos HAL it's a good idea to have at least a passing understanding of how the HAL interacts with the rest of the system.

通过修改eCos HAL，可以加深你对HAL与其他系统进行交互的理解。

HAL Classes

The eCos HAL consists of four HAL sub-classes. This table gives a brief description of each class and partly reiterates the description in Chapter 2 . The links refer to the on-line CVS tree (specifically to the sub-HALs used by the PowerPC MBX target).

eCos的HAL由四个HAL的子类构成。 此表给出了每一种类的简要说明：

HAL type	Description	Functionality Overview
Common HAL (hal/common)	所有的HAL配置选项和共享的功能。	通用的调试功能，驱动程序API，eCos与实时监控的调用接口，测试用例。
Architecture HAL(hal/<architecture>/arch)	架构相关的特定与通用实现。 以及可被Variant 与Platform  HAL层代码覆写的接口。	体系结构的调试器的功能（处理单步执行，异常跳转等），异常/中断向量的定义和处理程序，缓存定义和控制宏，上下文切换代码，汇编功能，早期的系统初始化，配置选项，测试用例。
Variant HAL(hal/<architecture>/<variant>)	CPU架构包括的一些变种，例如MIPS的CPU有32位与64位版本之分，变种CPU核心相关内嵌额外功能实现。	变异扩展的体系结构的代码（高速缓存，异常/中断），配置选项，变种架构设备的核心驱动程序。测试用例。
Platform HAL(hal/<architecture>/<platform>)	包含用户平台相关的功能和配置选项。	早期的平台初始化代码，平台内存布局规范，配置选项（处理器速度，编译器选项），诊断IO功能，调试IO功能，定制平台外围设备相关的差异化代码（外设中断处理），测试用例。
Auxiliary HAL(hal/<architecture>/<module>)	一些的变种有着共同的核心模块。 如：摩托罗拉的PowerPC与QUICC。	模块的具体功能（中断控制器，简单的设备驱动程序），测试用例。

File Descriptions

Listed below are the files found in various HALs, with a short description of what each file contains. When looking in existing HALs beware that they do not necessarily follow this naming scheme. If you are writing a new HAL, please try to follow it as closely as possible. Still, no two targets are the same, so sometimes it makes sense to use additional files.

下面列出的是在各种HAL文件，每个文件包含一个简短的描述。 在现有的HAL注意的是，他们并不一定遵循此命名方案。 如果你正在编写一个新的HAL，请尝试尽可能地遵循它。 然而，没有两个目标是相同的，所以有时会使用其他的额外文件。

Common HAL

File	Description
include/dbg-thread-syscall.h	Defines the thread debugging syscall function. This is used by the ROM monitor to access the thread debugging API in the RAM application. .
include/dbg-threads-api.h	Defines the thread debugging API. .
include/drv_api.h	Defines the driver API.
include/generic-stub.h	Defines the generic stub features.
include/hal_if.h	Defines the ROM/RAM calling interface API.
include/hal_misc.h	Defines miscellaneous helper functions shared by all HALs.
include/hal_stub.h	Defines eCos mappings of GDB stub features.
src/dbg-threads-syscall.c	Thread debugging implementation.
src/drv_api.c	Driver API implementation. Depending on configuration this provides either wrappers for the kernel API, or a minimal implementation of these features. This allows drivers to be written relying only on HAL features.
src/dummy.c	Empty dummy file ensuring creation of libtarget.a.
src/generic-stub.c	Generic GDB stub implementation. This provides the communication protocol used to communicate with GDB over a serial device or via the network.
src/hal_if.c	ROM/RAM calling interface implementation. Provides wrappers from the calling interface API to the eCos features used for the implementation.
src/hal_misc.c	Various helper functions shared by all platforms and architectures.
src/hal_stub.c	Wrappers from eCos HAL features to the features required by the generic GDB stub.
src/stubrom/stubrom.c	The file used to build eCos GDB stub images. Basically a cyg_start function with a hard coded breakpoint.
src/thread-packets.c	More thread debugging related functions.
src/thread-pkts.h	Defines more thread debugging related function.

Architecture HAL

Some architecture HALs may add extra files for architecture specific serial drivers, or for handling interrupts and exceptions if it makes sense.

Note that many of the definitions in these files are only conditionally defined - if the equivalent variant or platform headers provide the definitions, those override the generic architecture definitions.

File	Description
include/arch.inc	Various assembly macros used during system initialization.
include/basetype.h	Endian, label, alignment, and type size definitions. These override common defaults in CYGPKG_INFRA.
include/hal_arch.h	Saved register frame format, various thread, register and stack related macros.
include/hal_cache.h	Cache definitions and cache control macros.
include/hal_intr.h	Exception and interrupt definitions. Macros for configuring and controlling interrupts. eCos real-time clock control macros.
include/hal_io.h	Macros for accessing IO devices.
include/<arch>_regs.h	Architecture register definitions.
include/<arch>_stub.h	Architecture stub definitions. In particular the register frame layout used by GDB. This may differ from the one used by eCos.
include/<arch>.inc	Architecture convenience assembly macros.
src/<arch>.ld	Linker macros.
src/context.S	Functions handling context switching and setjmp/longjmp.
src/hal_misc.c	Exception and interrupt handlers in C. Various other utility functions.
src/hal_mk_defs.c	Used to export definitions from C header files to assembler header files.
src/hal_intr.c	Any necessary interrupt handling functions.
src/<arch>stub.c	Architecture stub code. Contains functions for translating eCos exceptions to UNIX signals and functions for single-stepping.
src/vectors.S	Exception, interrupt and early initialization code.

Variant HAL

Some variant HALs may add extra files for variant specific serial drivers, or for handling interrupts/exceptions if it makes sense.

Note that these files may be mostly empty if the CPU variant can be controlled by the generic architecture macros. The definitions present are only conditionally defined - if the equivalent platform headers provide the definitions, those override the variant definitions.

File	Description
include/var_arch.h	Saved register frame format, various thread, register and stack related macros.
include/var_cache.h	Cache related macros.
include/var_intr.h	Interrupt related macros.
include/var_regs.h	Extra register definitions for the CPU variant.
include/variant.inc	Various assembly macros used during system initialization.
src/var_intr.c	Interrupt functions if necessary.
src/var_misc.c	hal_variant_init function and any necessary extra functions.
src/variant.S	Interrupt handler table definition.
src/<arch>_<variant>.ld	Linker macros.

Platform HAL

Extras files may be added for platform specific serial drivers. Extra files for handling interrupts and exceptions will be present if it makes sense.

File	Description
include/hal_diag.h	Defines functions used for HAL diagnostics output. This would normally be the ROM calling interface wrappers, but may also be the low-level IO functions themselves, saving a little overhead.
include/platform.inc	Platform initialization code. This includes memory controller, vectors, and monitor initialization. Depending on the architecture, other things may need defining here as well: interrupt decoding, status register initialization value, etc.
include/plf_cache.h	Platform specific cache handling.
include/plf_intr.h	Platform specific interrupt handling.
include/plf_io.h	PCI IO definitions and macros. May also be used to override generic HAL IO macros if the platform endianness differs from that of the CPU.
include/plf_stub.h	Defines stub initializer and board reset details.
src/hal_diag.c	May contain the low-level device drivers. But these may also reside in plf_stub.c
src/platform.S	Memory controller setup macro, and if necessary interrupt springboard code.
src/plf_misc.c	Platform initialization code.
src/plf_mk_defs.c	Used to export definitions from C header files to assembler header files.
src/plf_stub.c	Platform specific stub initialization and possibly the low-level device driver.

The platform HAL also contains files specifying the platform's memory layout. These files are located in include/pkgconf .

Auxiliary HAL

Auxiliary HALs contain whatever files are necessary to provide the required functionality. There are no predefined set of files required in an auxiliary HAL.