Russell King - ARM Linux
linux at arm.linux.org.uk
Mon Jul 22 09:46:59 EDT 2013
On Mon, Jul 22, 2013 at 09:30:44PM +0800, zhaobin xv wrote:
> I recently read lernel source .
> I have a question:In
> .type start,#function
> .rept 8
> mov r0, r0
> b 1f
> .word 0x016f2818 @ Magic numbers to help the loader
> .word start @ absolute load/run zImage address
> .word _edata @ zImage end address
> 1: mov r7, r1 @ save architecture ID
> mov r8, r2 @ save atags pointer
> I don't kown why the “mov r0 r0 ” repeated emergence 8 times.
(a) boot loaders used to call the kernel at an offset of 32 bytes into
the image, but now call at the start of the image.
(b) the magic numbers are placed at a fixed position.
So we need to fill the first 8 words with something. They could have
all been branches to '1f' instead of that instruction. It makes little
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