Asus RT-AX53U overlay size

Hi, I recently bought Asus RT-AX53U as replacement for Archer C6 ( mainly because flash size ) but after installing 23.05.03 build of openwrt overlay partition is only ~33MB.

AFAIK this router supports dual firmware, but I don't need it and I would appreciate all the available NAND storage ( should be around 100MB ), can I do something about it w/o forking and building firmware myself?

You could wipe the 2nd firmware and add it as an extroot, but it wouldn't be the same partition as the default /overlay.

You can use USB stick without breaking revert to OEM

Are there any news about the "OpenWRT partitioning" and Asus RT-AX53U.

I installed the openwrt-23.05.4-ramips-mt7621-asus_rt-ax53u-squashfs-factory.bin using the commands:

mtd-write -i openwrt-23.05.4-ramips-mt7621-asus_rt-ax53u-squashfs-factory.bin -d Kernel -r

... and the /overlay partition is still about 33 MB big - instead of 90 MB.

Related PRs:

Details:

# df -h
Filesystem                Size      Used Available Use% Mounted on
/dev/root                 4.0M      4.0M         0 100% /rom
tmpfs                   121.4M      1.3M    120.0M   1% /tmp
/dev/ubi0_1              33.3M     22.2M      9.3M  71% /overlay
overlayfs:/overlay       33.3M     22.2M      9.3M  71% /
tmpfs                   512.0K         0    512.0K   0% /dev

# cat /proc/mtd
dev:    size   erasesize  name
mtd0: 00080000 00020000 "u-boot"
mtd1: 00060000 00020000 "u-boot-env"
mtd2: 00100000 00020000 "nvram"
mtd3: 00100000 00020000 "factory"
mtd4: 00100000 00020000 "factory2"
mtd5: 03200000 00020000 "firmware"
mtd6: 00400000 00020000 "kernel"
mtd7: 02e00000 00020000 "ubi"
mtd8: 03200000 00020000 "firmware2"
mtd9: 01020000 00020000 "jffs2"

Are there any steps which should be done to "maximize" the size of the /overlay partition?
(I do not need any backward compatibility with original Asus fw)

Thank you...

You have to edit dts file and compile a new FW using it.

Then you have to repartition flash using u-boot and flash your new FW.

Is there any official guide how to do it? Not just for this router, but most probably something generic?

Thanks...

No, and there's no generic way, since all devices are different.

Just as frollic told, there is not. It's totally up to you to do it.

But it's possible. I have one RT-AX53U and two 4G-AX56 devices. They use same basic HW. I have done this for all of them.

Actually there is a third model RT-AX54 using same basics, but it has flash configured as you want it.

An easy way to do it is taking suitable DTS parts from this AX54 and putting them into AX53U DTS file. Then compiling a new FW.

But as I told, it's only halfway then. You need serial connection to use U-Boot to make partition changes and then flashing tis new image.

If you then for some reason use Asus rescue tool to put it back to original FW, it also reverts flash partition changes.

How far you can push maintaining chances to revert?

It can always be quite easily reverted if only U-boot and calibration related parts are not wiped away.

Asus bootloader recovery is a bit picky about modified own ubi parts. I mean not restore flash to sales content but to casually reset back without extra gadgets...

If you have a backup, restore stock layout, using initramfs ?

Asus rescue does it anyways. I suppose it's ment to rescue it even if there are some new bad blocks.

Still the answer to the original question is, it's possible to take full advantage of the flash. Just like there already has been done by RT-AX54 version.

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