[U-Boot] Linux booting speed up.

Michele Venturi venturi at ebneuro.com
Wed Nov 19 17:04:51 CET 2008


I am using UBoot on a AT91RM9200 target supporting Linux 2.4.27.
I would like to accelerate the boot process, while keeping Kernel and 
RamDisk compressed on Flash EPROM.

10100000 address of compressed Kernel on Flash.
10200000 address of compressed RamDisk on Flash.
21100000 address of uncompressed RamDisk on SDRAM
bootcmd= cp.l 10200000 21100000 140010; bootm 10100000 21100000

Instead of copying the compressed RamDisk Flash code to SDRAM, and then 
instructing the kernel
to decompress the RamDisk, can U Boot uncompress the RamDisk on behalf of 
the Kernel, then presenting
the kernel with an uncompressed Ramdisk image ?
The idea is to skip the step of simply copying a compressed image from Flash 
to SDRAM,
but directly uncompressing the Flash image to SDRAM.

Sure this can be accomplished patching U Boot ad hoc, but can it be done 
through standard commands and variables ?

In other words, it would be great to uncompress a Flash image to a SDRAM 
address retrieved from its Load address,
leaving in SDRAM an uncompressed image (with an updated header of 
course)....

Thank you for your attention.






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