i.MX ProcessorsのトピックRe: U-Boot Environmental Variables

U-Boot Environmental Variables

ShaneKaiser — Wed, 27 Jun 2012 20:35:47 GMT

Hello Everyone,

I have a question regarding a U-Boot environment variable:

loadaddr=70800000

mmc read ${loadaddr} 0x800 0x1800; bootm

What exactly is the mmc command doing here? How does one come up with loadaddr=70800000?

From what I understand U-Boot will read data from the sd card at 2048*512=1MB (starting location of uImage on the sd card) and keep reading for 6144*512=3MB (the size of the kernel) and take this data and copy it to address 0x70800000 in memory? So U-Boot is installing the kernel at the memory address 0x70800000?

Re: U-Boot Environmental Variables

Yuri — Thu, 28 Jun 2012 05:42:25 GMT

You are right.

Re: U-Boot Environmental Variables

ShaneKaiser — Thu, 28 Jun 2012 05:52:44 GMT

Thanks for the response Yuri.

Why the memory address 0x70800000? I have noticed some people use other memory addresses. What is the thinking here?

Re: U-Boot Environmental Variables

Yuri — Thu, 28 Jun 2012 06:15:46 GMT

I am not sure if kernel decompressor is position independent, it may be build to use absolute addresses (0x70800000).