where are the SDK about 845c ? i need commplie the os ,bootloader、kernel 、 rootfs source code。
The release notes linked to from the release announcements should cover rebuilding (if you want to rebuild the rootfs then you want the OpenEmbedded release):
@zhaoyangyang12 We provide Debian and OE RPB images, As @danielt said, if you want to rebuild the full OS need to use oe-rpb-manifest with branch qcom/dunfell.
The OE RPB SDK is provided for application development.