Need for vmlinux being compressed???

[utteerna]

What is the reason for the vmlinux being compressed. Why take the trouble of compressing and then in boot code decompressing it and loading it

[blade2]

What is the reason for the vmlinux being compressed. Why take the trouble of compressing and then in boot code decompressing it and loading it

vmlinux is the uncompressed kernel binary image.

I think you mean vmlinuz (desktop kernel) or may be uImage (embedded kernel ) is decompressed by the boot code.

3 reasons:

1) In the early days, to allow the kernel to be placed on a 1.44 MB floppy disk. Compression takes up less space. Size is also important for embedded kernels on Flash based devices.

2) Kernel integrity checking. The decompression routine checks that decompressed kernel has the correct "checksum/CRC" value.

3) To allow a header to be added to the kernel image to indicate kernel name, size, and load address etc. for the boot code to use in extracting the kernel.