WNDR3700v4 enable unused memory

Yes, I have read wndr3700-related guides here, but my goal is not just to enable memory no-matter-what — I want to enable it while still being able to install binary packages, including kmod ones.

Do I understand it correctly that, if I build a custom firmware with the patch from here applied, then I'll lose the ability to use pre-compiled kmods from repos? If so, it's not an option.

The alternative solution is to simply mount the partition, right? It's okay, but how do I mount it?

[root@openwrt ~]# cat /proc/mtd 
dev:    size   erasesize  name
mtd0: 00040000 00020000 "u-boot"
mtd1: 00040000 00020000 "u-boot-env"
mtd2: 00040000 00020000 "caldata"
mtd3: 00080000 00020000 "pot"
mtd4: 00200000 00020000 "language"
mtd5: 00080000 00020000 "config"
mtd6: 00300000 00020000 "traffic_meter"
mtd7: 00200000 00020000 "kernel"
mtd8: 01700000 00020000 "ubi"
mtd9: 01900000 00020000 "firmware"
mtd10: 00040000 00020000 "caldata_backup"
mtd11: 06000000 00020000 "reserved"
[root@center ~]# mount /dev/mtdblock11 /mnt/
mount: mounting /dev/mtdblock11 on /mnt/ failed: Invalid argument
[root@openwrt ~]#

Mount fails with the Invalid argument error.
What am I doing wrong? Help pls.

mtd11 was likely not formatted so you cannot mount it until you format it with e.g. ext2/3/4.

The same link you mentioned talks about the potential risk of using mtd11.

If mtd11 is indeed safe to use, I thought ubifs would be nice but I don't know how to take advantage of it. I also heard about "mtd concat". No idea how to use this either.

Also this might help.

Thank you for the reply.

format it with e.g. ext2/3/4

No way you can do this — mtd devices are not designed to work with classic filesystems and you can't just format them with something like fdisk. I wish it was that easy, but no.

ubifs

Well, this seems to be a better option.
Looks like there are no straightforward guides on it though, so gotta do a research myself...

OP is back.

Good news: I managed to mount the partition with utilities from ubi-utils. Here's the log:

[root@openwrt ~]# ubinfo
UBI version:                    1
Count of UBI devices:           1
UBI control device major/minor: 10:59
Present UBI devices:            ubi0
[root@openwrt ~]# ubiattach /dev/ubi_ctrl -m 11
UBI device number 1, total 768 LEBs (97517568 bytes, 93.0 MiB), available 744 LEBs (94470144
[root@openwrt ~]# ubimkvol /dev/ubi1 -s 90MiB -N reserved
Volume ID 0, size 744 LEBs (94470144 bytes, 90.0 MiB), LEB size 126976 bytes (124.0 KiB), dyn
[root@openwrt ~]# ubiblock -c /dev/ubi1_0
[root@openwrt ~]# ls -l /dev/ubi*
crw-------    1 root     root      251,   0 Jan  1  1970 /dev/ubi0
crw-------    1 root     root      251,   1 Jan  1  1970 /dev/ubi0_0
crw-------    1 root     root      251,   2 Jan  1  1970 /dev/ubi0_1
crw-------    1 root     root      250,   0 Apr 26 16:15 /dev/ubi1
crw-------    1 root     root      250,   1 Apr 26 16:19 /dev/ubi1_0
crw-------    1 root     root       10,  59 Jan  1  1970 /dev/ubi_ctrl
brw-------    1 root     root      254,   0 Jan  1  1970 /dev/ubiblock0_0
brw-------    1 root     root      254,   1 Apr 26 16:20 /dev/ubiblock1_0
[root@openwrt ~]# mount -t ubifs /dev/ubi1_0 /mnt
[root@openwrt ~]# df -h /mnt
Filesystem                Size      Used Available Use% Mounted on
/dev/ubi1_0              81.4M     24.0K     77.2M   0% /mnt
[root@openwrt ~]#

Bad news: as you can see above, the drive has only 93M available (should be 96). Moreover, I can't create a volume larger than 90M (ubimkvol fails with No space left on device).
Also, lsblk still shows no mountpoint for /dev/ubiblock1_0 after doing mount -t ubifs /dev/ubi1_0 /mnt. However, it shows a mountpoint for /dev/ubiblock0_0 (which is the default overlay partition), so I'm likely doing something wrong.

Other things I have noticed:

mount -t ubifs /dev/ubiblock1_0 /mnt fails with Invalid argument, so have to mount /dev/ubi1_0 directly

Looks like occupied space doesn't recover:

[root@openwrt ~]# df -h /mnt
Filesystem                Size      Used Available Use% Mounted on
/dev/ubi1_0              81.4M     24.0K     77.2M   0% /mnt
[root@openwrt ~]# echo test > /mnt/deleteme
[root@openwrt ~]# df -h /mnt
Filesystem                Size      Used Available Use% Mounted on
/dev/ubi1_0              81.4M     28.0K     77.2M   0% /mnt
[root@openwrt ~]# rm /mnt/deleteme 
[root@openwrt ~]# df -h /mnt
Filesystem                Size      Used Available Use% Mounted on
/dev/ubi1_0              81.4M     28.0K     77.2M   0% /mnt

Is there anyone experienced in MTD/UBI? I'm afraid I can brick my router if I continue to figure things out myself.

Bump