[U-Boot-Users] help - u-boot header & compression

Wed Apr 2 23:57:05 CEST 2008

Hi Luigi

Thank you for your mail and comments. I should have explain why I want to compress u-boot. My target processor is Atmel AT91SAM9260. I am having a 64Mb Dataflash which is interfaced on SPI bus. The Atmel ARM9 copies the first 4kB to internal SRAM and then boots from there. So we need a loader of size <4kb which will be copied to SRAM. I have got this loader. This loader will invoke u-boot, and u-boot will invoke kernel. So I can compress loader and it will still work.

I'll compare nrv2b and lzma and then will be in a better position to comment. I chose nrv2b because I need a compression algo which can be as small as 600B (I have size restriction of 4kB).

Thanks
Avinash

----- Original Message ----
From: Luigi 'Comio' Mantellini <luigi.mantellini at idf-hit.com>
To: Avinash Vijayvergia <avinashs36 at yahoo.com>
Cc: u-boot-users at lists.sourceforge.net
Sent: Wednesday, April 2, 2008 2:37:20 PM
Subject: Re: [U-Boot-Users] help -  u-boot header & compression

    Hi Avinash,

see inline.

Il giorno mer, 02/04/2008 alle 14.26 -0700, Avinash Vijayvergia ha scritto:    Hi LuigI

    Thank you for your mail. I actually have two questions:            What is the format of u-boot header? Can you refer me to some documentation?    
What do you intend for "u-boot header"? U-boot uses the uImage format for the kernels images. You can check the file include/image.h (row 175) to understand the (old) uImage format. See this link: 
http://www.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=blob;f=include/image.h;h=36143e25acfe3684a751a4ee6a5cf945524ef424;hb=74d1e66d22dac91388bc538b2fe19f735edc5b82

            I want to compress u-boot. I have picked up nrv2b.c from Koders.com which is in use by many people :). I couldn't understand how it does encoding and decoding. I wanted to use this algo and do compression and decompression of my binaries. You can search google for nrv2b.c and you will get it from Koder.com.    
U-boot is the object code, the bootloader... how can you compress it? it is a non-sense for me. Anyway, if you need to compress the kernel image, you need to use the uImage format and the utility mkimage (see tools directory). I recently posted a patch to support the lzma compression algorithm (that works better than bzip2 and gzip): you can search in the mailing list archive to retrieve this patch.

Are you sure that nrv2b is better than powerful lzma or bzip2? Do you have benchmarks on this point? If you demonstrate me that nrv2b is a good choice I can consider to make the patch for the community... I have an application that has a very small flash memory... nrv2b should be a choice...

Best regards,

luigi

    Thanks for your help
    Avinash

    ----- Original Message ----
    From: Luigi 'Comio' Mantellini <luigi.mantellini at idf-hit.com>
    To: Avinash Vijayvergia <avinashs36 at yahoo.com>
    Cc: u-boot-users at lists.sourceforge.net
    Sent: Wednesday, April 2, 2008 2:19:36 PM
    Subject: Re: [U-Boot-Users] help - u-boot header & compression

    Hi Avinash,

    I'm not undestanding if you want compress the U-Boot code or if you want compress the uImage image.
    Anyway, I don't know the nrv2b algorithm, can you give me any links?

    thanks,

    luigi

    Il giorno mer, 02/04/2008 alle 13.54 -0700, Avinash Vijayvergia ha scritto: 
            Hi All

        I am working on AT91SAM9260 ARM9 core. I have very small flash memory and hence need to compress the u-boot. I have picked nrv2b algo for that. Can someone suggest me how to put the compression info in the u-boot header. I want to know the details of u-boot header too.

        Thanks
        Avinash

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Fax: +39 02 5167 2459
E-mail: luigi.mantellini at idf-hit.com

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