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从www.m-sys.com下载了DOC2000的驱动，tffs514-vxworks-bin.zip

阅读Readme过程中注意到以下这一段话


引用文字——
“There are two basic VxWorks boot scenarios supported by DiskOnChip driver:

A. One-step boot
This scenario is used with relatively small VxWorks applications
that can entirely fit into system's ROM.
In this case VxWorks bootimage, along with VxWorks, includes
application and DiskOnChip driver.
In case of x86 boards, this bootimage resides as a file BOOTROM.SYS
in root directory of the first disk partition on DiskOnChip. In all
other cases (PowerPC, MIPS board etc.) bootimage resides in board's ROM.

B. Two-step boot
This scenario is used with larger VxWorks applications where
scenario 'A' cannot be used because of application's size.
Two different bootimages are involved in this boot scenario - 'bootrom'
and 'vxWorks'.
The 'bootrom' bootimage includes minimal configuration of VxWorks
(which includes dosFs file system) and DiskOnChip driver; it does not
include user application itself. In case of x86 boards, 'bootrom'
bootimage resides as a file BOOTROM.SYS in root directory of the first
disk partition on DiskOnChip. In all other cases (PowerPC, MIPS boards
etc.) it resides in board's ROM. Essentially, 'bootrom' bootimage is a
program loader. It gets executed upon reset, and uses DiskOnChip driver
for loading the second bootimage - 'vxWorks' - from DiskOnChip. The
'vxWorks' bootimage includes the full configuration of VxWorks,
DiskOnChip driver, and user application.”

大意是：
VxWorks的启动方式有两种，一种叫One-Step boot（单步启动），应用于相对比较小的VxWorks程序中，
这种程序可以全部存储于系统ROM中。
另一种叫Two-setp boot（双步启动），这种情况下VxWorks程序相对较大，单步启动方式就不适用了。

我的理解是这样子的，对于有ROM的嵌入式系统，这两种方式有明显区别，若应用程序足够小，能全部容纳于ROM中，即可把bootimage和vxworks全部下载到ROM中，

而对于双步启动，由于应用程序比较大了，rom仅能容纳bootimage，
vxworks下载到RAM中，系统控制权经由bootimage转交VxWorks。

而对于x86架构，由于bootimage需要以bootrom.sys的形式存储于引导分区上，所以都是双步启动的。单步启动和双步启动没有多大区别。

自己的理解很别扭的感觉，也不知道对不对。大家是怎么理解“单步启动”和“双步启动”这两个概念的呢？

或者能给我一个vxWorks在单步启动时的例子么？

谢谢

[align=right][color=#000066][此贴子已经被作者于2006-3-8 13:31:44编辑过][/color][/align]