Asus RT-AC58U RAM limit

Hello, a have a little question, whrere in source code of OpenWRT for asus rt-ac58u sets ram limit?

i solder new ram chip NANYA NT5CC128M16IP-DI
old ram chip was NANYA NT5CC64M16IP-DI
but router still see only 128 mb ram

In asus source code i found in u-boot this limit, but i dont understand how to write compiled new u-boot.img to stock firmware.

what values i should set for 256mb ram? if you know ofcourse.

I think I got it:
if second value 0x8000000 convert to DEC = 134217728 bytes = 128 mb

for 256 mb i need convert 268435456 to HEX = 0x10000000

Unfortunately it didn’t help, maybe I wrote incorrect data.
But anyway thanks to help, maybe someone know correct data.
Maybe there are some other files where the memory size is set.

I see the EA8300 using same NANYA NT5CC128M16IP-DI 256MB chip.
The memory offset in dts look like

memory {
		device_type = "memory";
		reg = <0x80000000 0x10000000>;

I found solution.
What we need:

  • official asus sources code
  • usb uart
  • tftpd server
  1. unpack sources
  2. extract asuswrt/tools/openwrt-gcc463.arm.tar.bz2 to /opt
  3. export PATH=/opt/openwrt-gcc463.arm/bin:$PATH
  4. export STAGING_DIR=/opt/openwrt-gcc463.arm

go to
make rt-ac58u_256MB_config

and we get two files:

  • u-boot_norplusnand.img (we need this file)
  • u-boot_norplusnand.trx

interesting thing about file u-boot_norplusnand.trx (i dont know for what this file)
if in stock firmware:
cp /dev/mtd0 /tmp/mtd0.bin and copy it to pc
size = 2Mb or 2 097 152 bytes which equals with this file


in uart console choose 9 option (when router starting)

Please choose the operation:
1: Load System code to SDRAM via TFTP.
2: Load System code then write to Flash via TFTP.
3: Boot System code via Flash (default).
4: Entr boot command line interface.
7: Load Boot Loader code then write to Flash via Serial.
9: Load Boot Loader code then write to Flash via TFTP.
3: Boot System code via Flash (default).

and upload file u-boot_norplusnand.img

finish. now we have 256Mb ram in RT-AC58U

i did all this operations with stock firmware.
then updated to OpenWRT (ram is still 256Mb)

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