Wiki cleanup: MikroTik RB750r2 (hEX lite) - outdated page + question about 64MB RAM warning

Talk about Documentation
1

Hi all,

@tmomas - two issues regarding the MikroTik RB750r2 (hEX lite) wiki page.

Starting point: Mikrotic hex lite fail on sysupgrade

User tried to flash 25.12.0 - the initramfs boots fine, but the sysupgrade image is too large to fit in free RAM while the initramfs is running (64 MB device). 24.10.4 works, confirmed by user.

Issue 1: ToH shows 25.12.0 as current release

Should be corrected to 24.10.4, with a note that 25.x fails due to RAM constraints.

Note: The Firmware Selector actively offers 25.12.0 - including kmod-ath9k despite no WLAN hardware:

A custom build via the Firmware Selector without these packages might work - but requires knowledge that regular users don't have.

Issue 2: Wiki page still ar71xx era (2017)

Still references ar71xx images that no longer exist. Device has been on ath79/mikrotik since 18.06.0.

Question: Would a general 64MB RAM warning on affected device pages make sense - similar to the existing 4/32 warning?

2

to be precise, for the 25.12.0, the initframs works but the sysupgrade does not work

for the snapshot, the initframes didn't even work but the images looked smaller

3

Thanks for the clarification!

So to be precise:

  • 25.12.0 initramfs boots fine
  • 25.12.0 sysupgrade fails - too large to fit in free RAM while initramfs is running
  • Snapshot initramfs does not boot - image even larger
4

BTW, a quick look at the account says the user is no longer active (but I think they may still participate in extra-forum portions of the project).

It's quite common in the forums to suggest using older versions to convert to OpenWrt when issues like this are experienced with newer images.

  • If someone drafts verbiage, I'm sure one of us with Wiki edit privileges can update it for you.
  • Images no longer exist?
5

@lleachii

Regarding "Images no longer exist?" - yes, confirmed. All links on the current wiki page return 404:

https://archive.openwrt.org/snapshots/trunk/ar71xx/mikrotik/openwrt-ar71xx-mikrotik-vmlinux-initramfs.elf
404 Not Found

https://downloads.openwrt.org/snapshots/targets/ar71xx/mikrotik/openwrt-ar71xx-mikrotik-rb-nor-flash-16M-initramfs-kernel.bin
404 Not Found

https://downloads.openwrt.org/snapshots/targets/ar71xx/mikrotik/openwrt-ar71xx-mikrotik-rb-nor-flash-16M-squashfs-sysupgrade.bin
404 Not Found

https://lede-project.org/docs/guide-quick-start/developmentinstallation
404 Not Found

Regarding the warning box - the existing 8/64 warning box does not apply here. The device has 16 MB flash and 64 MB RAM. Flash is not the issue - only the RAM is the bottleneck when flashing newer images.

The existing warning boxes do not cover this case:

  • 4/32 warning - does not apply
  • 8/64 warning - does not apply, wrong flash value

Devices like this are effectively masked - they fall through all existing filters because their flash is sufficient.

Suggested warning text for the RB750r2 page:

"Note: This device has only 64 MB RAM. Starting with OpenWrt 25.x, the sysupgrade image is too large to fit in free RAM while the initramfs is running. The last confirmed working release is 24.10.4."

Question: Would a new standardized warning box for devices with sufficient flash but insufficient RAM make sense? There may be more affected devices with the same issue.

6

Most of the links you provided have been invalid for quite some time (although, they used to redirect appropriately). Definitely needs to be fixed.

That may be a good idea.

7

Thanks for the quick feedback!

For the dead links - if you are able to fix those directly, that would be great. Otherwise I am happy to help if you can point me in the right direction.

For the warning box - is there a preferred process for proposing new wiki templates? Should I open a separate thread for that, or is this the right place to continue the discussion?

8

warning box says:

This device does not have sufficient resources (flash and/or RAM) to provide secure and reliable operation.

added to wiki page.

1 Like
9

Thanks for the quick action!

Two small points:

First: the RB750r2 has 16 MB flash, not 8 MB. The 8/64 warning box does not quite fit here - flash is not the issue on this device, only the RAM is the bottleneck when flashing newer images.

Second: the dead links on the wiki page are still there.

The reason this matters: this whole thread started because a user downloaded 25.12.0, spent time troubleshooting, needed forum support, and ended up reinstalling 24.10.4. With correct information on the wiki page that would have been avoidable.

A more general warning without a hardcoded flash value would cover this case correctly and would also be reusable for other devices. Happy to help draft the warning text or contribute directly.

10

That's why it says and/or.

In German ?

,)

So basically the initramfs of 25.12 is fine, but newest flashable image is 24.10.4 ?
I can make the update, once you confirm.

11

Confirmed, with one correction: the last working version is 24.10.5, not 24.10.4 - apologies for the mix-up.

As tested and reported by the user in the original thread:

  • 25.12.0 initramfs: boots fine
  • 25.12.0 sysupgrade: fails (7.2 MB - too large)
  • 24.10.5 sysupgrade: works (6.8 MB)
  • Snapshot: does not work either

https://forum.openwrt.org/t/mikrotic-hex-lite-fail-on-sysupgrade/247699

1 Like
12

OK, wiki updated, please check.

If you feel like testing, try booting an older initramfs, like really old, then try flashing the 25.10 sysupgrade.

1 Like
13

Agreed, the Meraki MR12 has same flash and ram and upgrades smoothly, does take an age to boot though.

14

Thanks for the quick update!

The changes look good overall. One remaining question: the "Supported Current Rel" field still shows 25.12.0. Does this need to be updated manually, or is it pulled automatically from somewhere else?

15

it's pulled from the hwdata page.

I've put the device as EOL in https://openwrt.org/toh/hwdata/mikrotik/mikrotik_rb750_r2, and added the 24.10.5 image links. It should soon be updated on the wiki page, but I'm not sure what exactly the EOL flag will do, I hope it makes the version remain 24.10 when newer versions are released...