• 欢迎访问开心洋葱网站,在线教程,推荐使用最新版火狐浏览器和Chrome浏览器访问本网站,欢迎加入开心洋葱 QQ群
  • 为方便开心洋葱网用户,开心洋葱官网已经开启复制功能!
  • 欢迎访问开心洋葱网站,手机也能访问哦~欢迎加入开心洋葱多维思维学习平台 QQ群
  • 如果您觉得本站非常有看点,那么赶紧使用Ctrl+D 收藏开心洋葱吧~~~~~~~~~~~~~!
  • 由于近期流量激增,小站的ECS没能经的起亲们的访问,本站依然没有盈利,如果各位看如果觉着文字不错,还请看官给小站打个赏~~~~~~~~~~~~~!

Memory support in VxWorks

嵌入式开发 弦苦 2196次浏览 0个评论

1 Main memory RAM configuration:

Zeroed at power-up for cold-boot to prevent parity errors.

Configured and enabled by ROM code at system power-up.

 

2 Cache memory RAM configuration:

Usually disabled at power-up, enabled by VxWorks pre-kernel initialization code.

Provide cache management libraries.

For some architectures the instruction cache is enabled at power-up for faster VxWorks boots.

 

3 ROM – Non-volatile property allows:

System boot code storage.

Hardware environment configured to jump to a ROM address atpower-up.

To program a ROM, it is removed from hardware environment and taken to a ROM “burner”.

 

4 Flash

(1) Flash is non-volatile memory which can be modified programmatically.

(2) Used as a “silicon” hard disk:

<1> System boot code storage.

<2> Hardware environment configured to jump to a flash address atpower-up.

<3> Maintaining data integrity during power-outs.

<4> Access times slightly slower than DRAM but faster than

ROM.

 

5 Flash vs PROM

(1) Flash and ROM use similar memory cell technology:

<1> Storage transistor employs transistor tunnelling.

<2> No battery to provide non-volatility.

<3> Access times are roughly the same.

(2) Flash power supply unit allows flashto be modified without being removed from hardware environment.

<1> Contents may be modified over a network interface.

<2> Contents may be modified by application code.

<3> ICE maybe a savior when bootloader within flash crash.

(3) Many hardware environments use jumpers to configure:

<1> System to jump to a flash address or a PROM address atpower-up.

<2> Size of on board flash/PROM.

 

6   NVRAM

(1) Non-volatile RAM:

<1> Non-volatility usually provided by battery.

<2> May be implemented using CMOS RAM, battery-backed SRAM, or flash.

(2) Units may contain a programmable time-of-day (TOD) clock:

<1> TOD information is stored inNVRAM.

(3) Used to store boot parameters for VxWorks image:

<1> VxWorks boot parameters may useup 255 bytes.

(4) If a hardware environment does not have NVRAM, boot parameters are statically linked into boot code.

 

Declaration:

Excerpt from Chapter 2 System Hardware, 2.4 Memory Of 《Tornado BSP training workshop


开心洋葱 , 版权所有丨如未注明 , 均为原创丨未经授权请勿修改 , 转载请注明Memory support in VxWorks
喜欢 (0)

您必须 登录 才能发表评论!

加载中……