openwrt/target/linux/gemini/image/copy-kernel/copy-kernel.S

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ArmAsm
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// Arm assembly to copy the Gemini kernel on Storlink reference
// designs and derived devices with the same flash layout and
// boot loader.
//
// This will execute at 0x01600000
//
// Copies the kernel from two fragments (originally zImage
// and initramdisk) to 0x00400000 making space for a kernel
// image of up to 8 MB except for these 512 bytes used for
// this bootstrap.
//
// 0x01600200 .. 0x017fffff -> 0x00400000 .. 0x005ffdff
// 0x00800000 .. 0x00dfffff -> 0x005ffe00 .. 0x00bffdff
// Memory used for this bootstrap
.equ BOOT_HEADROOM, 0x200
.global _start // Stand-alone assembly code
_start:
mov r1, #0x01600000
mov r2, #0x00400000
mov r3, #0x00200000
add r1, r1, #BOOT_HEADROOM
sub r3, r3, #BOOT_HEADROOM
copyloop1:
ldr r0, [r1]
str r0, [r2]
add r1, r1, #4
add r2, r2, #4
sub r3, r3, #4
cmp r3, #0
bne copyloop1
mov r1, #0x00800000
mov r3, #0x00600000
copyloop2:
ldr r0, [r1]
str r0, [r2]
add r1, r1, #4
add r2, r2, #4
sub r3, r3, #4
cmp r3, #0
bne copyloop2
mov r0, #0x00400000
// Let's go
mov pc, r0