openwrt/target/linux/gemini/image/copy-kernel/copy-kernel-2048k.S
Linus Walleij 691aa70e16 gemini: create a copy-kernel for 3072k kernels
The Raidsonic devices do not use a 2048k kernel "Kern"
partition like the Storlink reference designs. Instead
it uses a 3072k partition to fit a slightly
larger kernel.

Sadly the current OpenWrt Gemini kernel is still bigger
than 3072k so we need to make use of the Ramdisk
partition as well.

Create a special "copy-kernel" version that can deal
with the Raidsonic 3072k kernels. Tested on the
Raidsonic IB-4220-B booting kernel v6.12.66.

Fix a copy/paste error in the image generation makefile
while we are at it.

Link: https://github.com/openwrt/openwrt/pull/21686
Signed-off-by: Linus Walleij <linusw@kernel.org>
2026-01-25 19:08:01 +01:00

45 lines
1 KiB
ArmAsm

// 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