Compersssion method used in zImage in Linux SDK 8.0

lyf sci

Genius 3720 points

Hi Experts,

What is the compression ratio and the advantage of using zImage in the Linux SDK 8.0 ?

To reduce boot time is it possible to use the uncompressed kernel and what is the procedure for the same ?

0 Kemal R. Shakir over 10 years ago

Hello Lyf,

The zImage in SDK 8.0 is compressed with gzip compression which reduces the kernel size approximately 58%.
In some cases, if you have a fast processor and slow background memory loading the uncompressed kernel might improve the boot time. Otherwise the compressed approach will be faster.
Here you can find the procedure for loading an uncompressed kernel on ARM.

You may also get interested in the following two presentations, which describes and compares the advantages and disadvantages of different compressions.
events.linuxfoundation.org/.../lcjpcojp13_klee.pdf
free-electrons.com/.../arm-xz-kernel-decompression-benchmarks

References:
morgue.openinkpot.org/.../ZImageFormat
free-electrons.com/.../uncompressed-linux-kernel-on-arm
elinux.org/Uncompressed_kernel

Best regards,
Kemal

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