2008-07-05 11:43:48     Booting process sequence doubt

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2008-07-05 11:43:48     Booting process sequence doubt

Appalayagari Sreedhar (INDIA)

Message: 58383   

 

Hi,

 

Builded uImage information for my custom board is as follows.

 

Image Name:   uClinux Kernel and ext2

   Created:      2008-06-27  14:03:44 UTC

   Image Type:   Blackfin Linux Kernel Image (gzip compressed)

   Data Size:    5899043 Bytes =  5.6 MB

   Load Address: 00300000

   Entry Point:  00300000

 

I understood from the FAQ, the Load address and Entry Point.

 

when i give the command

 

tftp 0x1200000 uImage;bootm , booting of the kernel starts at the address 0x1200000

 

how the booting process happens in this case. Can anyone explain me the booting process sequence in this case.

 

Thanks and Regards,Sreedhar.

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2008-07-05 17:37:16     Re: Booting process sequence doubt

Frank Van Hooft (CANADA)

Message: 58385   

 

I don't believe the kernel is actually booting from address 0x1200000. Rather, my understanding is that when you executed this command:

 

tftp 0x1200000 uImage

 

, U-Boot grabbed your uImage file over the network & stored it into RAM starting at address 0x1200000. Note that a uImage file is a compressed file.

 

Then when you execute the command:

 

bootm

 

U-Boot goes and finds your uImage file, and uncompresses it into the address ranges that the contents of the uImage file dictate. So at the end of the decompression stage there will be code loaded in memory at 0x300000 for example. (It's not just decompression by the way; U-boot does a bunch of other preparatory things as well, to get the environment ready for linux to boot).  Then, when everythng's set up. it jumps to the linux start address.

 

 

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2008-07-06 11:22:53     Re: Booting process sequence doubt

Robin Getz (UNITED STATES)

Message: 58388   

 

Sreedhar:

 

Have a look at:

 

https://docs.blackfin.uclinux.org/doku.php?id=bootloaders:u-boot:uimage#bootm

 

Which describes things pretty much exactly like Frank did.

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2008-07-07 03:04:49     Re: Booting process sequence doubt

Appalayagari Sreedhar (INDIA)

Message: 58394   

 

Dear Frank and Robin,

 

Thankyou very much.

 

Best Regards,Sreedhar.

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