I've read the changelog of the newly released 19.07 which highlights the transition from ar71xx to ath79. I've been using OpenWrt for as long as... a month, and don't know what a target is, can someone explain?
After getting a brief overview of what a target is, I would like to know why my devices are missing on the 19.07 release:
TL-WR740N v4 - only initramfs image is available
TL-WR741ND v4 - only initramfs image is available
TL-WR841N v10
Are they simply not supported anymore, or just because OpenWrt 19.07 needs some more modifications to work on them, and no one has done that yet?
In OpenWrt slang, a target usually refers to a specific family of SoCs sharing the same or very similar CPU cores and instruction sets which are used among a range of different router models.
The ar71xx target for example refers to a series of MIPS CPU based SoCs first produced by Atheros (hence the AR prefix) and later Qualcomm.
The reason why your particular models are missing is due to the fact that OpenWrt keeps growing with each version, and 19.07 is one of the first release to be too big to fit in to 4MB flash devices without further modifications.