答: 往/etc/opkg/distfeeds.conf中添加需要的源即可,示例如下:
$ cat /etc/opkg/distfeeds.conf
...
src/gz openwrt_base http://downloads.openwrt.org/snapshots/packages/aarch64_generic/base
...
src/gz openwrt_packages http://downloads.openwrt.org/releases/packages-19.07/aarch64_generic/packages (這是新增的源)
...
$ opkg update