kernel startup

[Kumar Gala]

> > Normally is it the uboot that uncompresses the kernel or the kernel
> uncompress itself? 
> 
> >>How would something compressed uncompress itself?  If u-boot is being
> used 
> >>it will uncompress a compressed kernel and put the image at physical
> 0.
> 
> Small correction. Just like a self extracting binary, a kernel can have
> a decompression code prepended to the start of kernel which can
> decompress the 
> Kernel.  This is how redboot for xscale is structured or syslinux /lilo
> for x86. 

This also happens with the boot wrapper that is in arch/{ppc,powerpc}/boot

> 
> Although u-boot has simplified this step by doing the CRC checksum of
> the
> uiMage header as well as data and also decompress the kernel. Based on
> load
> address, entry point, the kernel can start executing.  
> 
> Now, whether cache is enable or not, MMU is enabled/disabled depends on
> the
> Developer. In current u-boot, the MMU is not used. I-Cache is On and
> D-cache
> is off.

I'm not sure what sub-arch we are talking about, but some do have the MMU 
on.

- kumar