EA8500: Possible way to expand its free space

Installing and Using OpenWrt
1

Hi forks,

The Linksys EA8500 comes with 128MB raw flash, and its default dual-os flash layout leaves around 40MiB for each OpenWRT system installed. This results in approximately 23MiB of space for the overlay to install additional software:

root@OP:~# df -h
Filesystem                Size      Used Available Use% Mounted on
/dev/root                 7.0M      7.0M         0 100% /rom
tmpfs                   232.6M    100.0K    232.6M   0% /tmp
/dev/ubi0_1              21.4M    204.0K     20.1M   1% /overlay
overlayfs:/overlay       21.4M    204.0K     20.1M   1% /
tmpfs                   512.0K         0    512.0K   0% /dev

However, one may need 50MiB for the software. Is there a way to achieve this?

I tried using a USB dongle as its external overlay, and it works, but it doesn't seem stable—sometimes it may fail to reboot to the system.

I was wondering about the possibility of extending the overlay to the space allocated for the 2nd OpenWRT system. This way, there would be only one copy of OpenWRT installed on the router, and its overlay space could be extended as much as possible..

Many thanks

2

The short answer is: no.

From a purely technical/ theoretical point of view, you 'could' change the bootloader and repartition the device, but this would be a very dangerous approach with (almost) no way back, doing so would imply:

  • risk of hard-bricking
  • changing the bootloader/ -~settings
  • building modified OpenWrt versions 'forever', as the partitioning is hardcoded in the DTS files (meaning you have to adapt it to your modified layout)
  • no way to return to the OEM firmware (at least no reasonably easy one)
2 Likes
3

I also think the dual partition is a waste of space and not many people want to go back to stock ever but @slh gives the sensible answer.

I must admit that I looked into it, I compile my own builds and know where to find the .dts file and know a bit how it works but not enough to risk hard bricking my EA8500 as it is in use as WG and OpenVPN server

4

Same for the Asrock G10, but you already know that ;- ) Another way of making use of the "useless" OEM partition would be two different OpenWrt versions e.g. one stable the other testing and an easy way to choose between.

Can you estimate the amount of difficulty / labor to archive this?

5

Not trivial, but it should be possible; the ea8500 should already have that.

6

V23.05.0 had problems restarting
but v23.05,2 seemed to fix that
I'd change your USB stick if it still has problems
I have use the ext-overlay for months without fault
it's a bit trickery to update versions but works fine & can add swap space at same time
I needed this to run asterisk & it did fine
I have since upgraded my connection & the ea8500 was not quick enough
so mini pc it is now. the ea8500 is a dump AP
FYI it was a USB 2.0 plunged into the combo SATA port
with a usb3.0 HDD plugged into the USB port using samba

7

Hi forks,
Many thanks for the advices.

Currently, installed the OpenWRT v23.05.2 to the router and the 32 GB USB driver were mounted as its external root device (rather than overlay only). There are 4 reboots in the past week, and no issues have been found.

Thank you, @slh @egc @Doppel-D @Lucky1