Imagebuilder fails for ramips/mt7621 (cudy wr1300v3)

For Developers
1

Hi all. I'm not sure if this is the right category to post this, but I think this information can be useful to some openwrt users.

Yesterday (Sun Jan 13) I attempted to build an image using openwrt-imagebuilder-ramips-mt7621.Linux-x86_64.tar.xz from snapshots:

make image PROFILE="cudy_wr1300-v2" PACKAGES="kmod-mt7603 kmod-mt7615e kmod-mt7663-firmware-ap luci -uboot-envtools"

I tweaked the default PROFILE by including luci. Building the image went smoothly, resulting in:

openwrt-ramips-mt7621-cudy_wr1300-v2-squashfs-sysupgrade.bin

This uploaded fine using Luci, but the upgrade as such failed and resulted in a flashing power LED. I had to do a TFTP recovery to get the device running again.

Note: I'm actually having a WR1300v3 which has a known tx power issue (but is almost 100% the same as WR1300v2) that may have been solved in recent snapshots. The router is currently running v2 firmware since no v3 is available yet, and it felt like the safest choice to bult a v2 image as a first step.
Note: I'm aware of several older reports about imagebuilder failing. So this may not be newsworthy, in which case it can be ignored. But that raises the question if there should be a big(ger) disclaimer when using imagebuilder.

2

Replying to my own post, since I got it running now. In hindsight there is a clue on the Using the Image Builder page: "The Image Builder has similar prerequisites as the Build system." which probably implies that "umask 0022" is required. So before the tar command in the "Unpack the archive and change the working directory: " do "umask 0022".