Space considerations on the Firebox M300

Installing and Using OpenWrt
1

I got my Firebox M300 working on Openwrt 25.12.5 - i had a few 'head-scratching' moments along the way, but i figured it out with the help of your earlier posts & also those in that 'Report' thread - so thank you for your assistance.

However, i've now got two queries which I don't know enough about to answer:

  1. In my Luci Status Overview page for the System, it shows "Storage Disk Space: 19.34MiB / 98.33MiB (19%)" but "Temp Space: 3.12MiB / 1.93GiB (0%)". So that seems to be telling me i've only got about 100Mb of available space for adding additional packages but a bucket-load of empty 'temp' space? Is there a simple way to reallocate the temp space as storage? Can i just 'resize' partitions on the SDcard before booting?? Or is it a complex procedure involving overlays etc etc?
  2. I tried to install 'AdGuard Home' package, but it appears not to be available. When I use the Openwrt Firmare Selector to build a custom Firebox M300 image and include package 'adguardhome', it generates an error: "RuntimeError: Impossible package selection: missing (adguardhome)". Is this because the adguardhome package has not been pre-built for the M300's QorIQ architecture and therefore simply isn't available? I dont have the skills to build/compile openwrt packages, so that would be something of a problem as AdGuardHome on the M300 was the whole reason I bought the thing :frowning:
2

Temp space is RAM.

3

I dont think Temp Space is RAM is it? Because the Status page shows me I have just under 4Gb of available Memory??

Firebox-1
Firebox-1719×637 17.5 KB

4

Zeroes compress very well, try saving a large ZIP in the /tmp folder.

5

What's the point of filling up /tmp with a large zip, if it still doesn't allow additional disk storage space for installing additional packages using the Luci web UI?

6

Not what I was after, forget the ZIP.

https://openwrt.org/docs/guide-user/additional-software/extroot_configuration create an additional partition for the extra data you're going to store.

Not sure it's been tested on the M300 earlier, trial and error.

7

Using the Firmware Selector to 'request' older builds for the M300, seems to confirm that package 'adguardhome' has never been available for the M300 :confounded_face:

I think I'll be listing my M300 on eBay in that case :sad_but_relieved_face:

8

Unless you need the fancy AGH UI, simply install one of the AdBlock packages available, and use the same block lists.

Same result, 65MB flash space saved.

9

I was looking at Adblock-fast before, but I don't think it has the 'fancy' charts & lists that AdguardHome provides?

Also, I had previously used AdGuard Home with several upstream DNS using HTTPS, TLS & QUIC - does Adblock allow you to specify several Upstream resolvers using different protocols??

I might try SmartDNS as it does some of what I wanted (ie. Upstreams using DoH, TLS, QUIC etc) but it seems to have issues when it comes to downloading/updating community block lists (see my GitHub issue here: https://github.com/pymumu/smartdns/issues/2461)

10

That's what I meant by fancy UI.

You can use https-dns-proxy, but it's probably only DoH capable.

11

I'll try downloading a custom image for my M300 with SmartDNS included as I've had some success with that before & using it with upstreams NextDNS and AdguardDNS (the cloud version).

Any idea how I increase the tiny 100Mb disc storage space for my M300 OpenWrt install? I think 100Mb for downloaded packages is just too tiny to be workable, especially as theres over 1Gb of /tmp doing nothing useful.

12

You've been given the link.

I don't think /tmp can be shrunk without building your own image.

13

This worked like a champ for me:

Screenshot from 2026-09-14 22-16-50
Screenshot from 2026-09-14 22-16-501208×864 60.5 KB

14

Looks like no ppc64 big endian support from adguard home which is probably why it isn't built for openwrt. Might be a deep rabbit hole...

15

A little further down that hole it looks like the CPU doesn't support POWER8 and go requires that to compile for ppc64 BE (and LE). So nothing written in go is likely to work on the M300. AGH is written in go. Boo.

16

Try doing an inplace upgrade to 25.12.5 using OWUT.

17

It's already running 25.12.5. But you mean it's likely to fail after expanding root?

18

then downgrade to 25.12.4 for a minute.

I'd love to be wrong, let us know.

19

I'm not entirely sure what an "in place upgrade" means or how to use OWUT (I'm a reasonable novice with OpenWrt).

I'll try running the script on my existing 25.12.5 install & see what happens. If it goes wrong, I'm presuming I can always create a new OpenWrt SDcard & boot the Firebox using the new card? If I do that, will it dump me in UBoot & I have to repeat the various 'setenv' commands at the start of this thread to get OpenWrt to boot? Or are those commands now permanently stored somewhere in UBoot & never need repeated??

Which then makes me wonder, if I just reinserted the original Watchguard Firebox SDcard with their original image still on, will that boot their OS or will it fail because it's expecting OpenWrt?

20

you can even use the same card, no need to throw it away :slight_smile:

I don't own the device, but I'd guess they're not stored on the SD.

depending on which uboot settings were changed (I haven't checked), it might not boot.