how does imx28 ocrom and ocram work?

[erickhuang]

hello,

I recently see the imx28 the reference manual, but I had a problem.As follows,

ocram:   0x0000 0000   ~    0x0001 FFFF

ocrom:   0xFFFE 0000   ~ 0XFFFF FFFF

I do not understand how he is working during power-up, the cpu pointer is pointing where , OCROM or OCRAM.

In addition, Where the boot image data loaded?

I learned that the ocrom  inside has a loader code, so  the code  is already written into the chip Manufacturers？？？

[imxcommunitysco]

CPU run at 0x0 – OCROM when power on.

ROM code will decode bootstream file.

There is a header in bootstream file,  which decide where will be loaded.

[AnsonHuang]

On MX28, when power up, ARM pointer is reset to high addr, 0xffff0000 where is ROM located.

Yes, ROM code is written into chip, atually, ROM code is part of IC design.

ROM code will be running and load the bootloader from SD/NAND/FLASH etc. to OCRAM, then jump to OCRAM to run the bootloader.

[erickhuang]

Hello Yongcai,

Thanks for your answer, and it is very helpful to me.

In recent days, I was learming the Reference Manual, I met a few questions, can you help me?

The first question, when power-up, if failed to start, the system will enter the recovery mode, I am not very understanging this mode specific is how to use it.

Another problem is that I don't know to secure boot.

Best wishes.

[AnsonHuang]

Hi, Erick

Recovery mode means, ROM enter serial download mode, you can use sb_loader to load image to ocram to run.

Secure boot is transparent, ROM will check this IVT header, you only need to build your image with IVT, like what we release, we have two boot loader, one with IVT, the other without IVT.

发自我的 iPad

在 2012-10-12，20:57，"erick huang" <admin@community.freescale.com<mailto:admin@community.freescale.com>> 写道：

Freescale Community<https://community.freescale.com/index.jspa>

how does imx28 ocrom and ocram work?

created by erick huang<https://community.freescale.com/people/erickhuang> in i.MX Community - View the full discussion<https://community.freescale.com/message/303124#303124>

[erickhuang]

Hi Yongcai,

As you say,We release two boot loader,one with IVT,the other without IVT.

so, when not need the secure boot feature, use only the boot loader whitout IVT ?

[AnsonHuang]

I think so. You can fuze the chip to disable HAB, then no longer need IVT image.

发自我的 iPad

在 2012-10-12，21:17，"erick huang" <admin@community.freescale.com<mailto:admin@community.freescale.com>> 写道：

Freescale Community<https://community.freescale.com/index.jspa>

how does imx28 ocrom and ocram work?

created by erick huang<https://community.freescale.com/people/erickhuang> in i.MX Community - View the full discussion<https://community.freescale.com/message/303144#303144>