Linux/PROCESSOR-SDK-AM335X: Debian port

No, you already have found the revision. Here am posting you the exact steps to port Debain Linux on AM335x Starter Kit Rev 1.2B.

First download this archive and extract it. Double click and mount the bone-debian-9.1-lxqt-armhf-2017-08-31-4gb.img on your host machine. Download the latest Processor SDK, edit <Processor SDK>/bin/create-sdcard.sh line 1050 change sudo cp -r to sudo cp -rp in order to preserve the specified attributes then run it. Choose to enter in custom boot and rootfs file paths. Copy the MLO and u-boot.img from the Processor SDK into a separate directory and pass that directory path when the script asks for boot partition and choose to reuse kernel image and device tree files found in the selected rootfs, for the rootfs pass the mounted bone-debian-9.1-lxqt-armhf-2017-08-31-4gb.img partition (generaly /media/<username>/rootfs since Ubuntu 16.04)

Then when the copying completed, put the SD card to the starter kit, press power on button and stop the booting in U-Boot console.
Enter these commands:
=> setenv bootfile vmlinuz-4.9.45-ti-r57
=> setenv findfdt 'if test $board_name = A335BONE; then setenv fdtfile am335x-bone.dtb; fi; if test $board_name = A335BNLT; then setenv fdtfile am335x-boneblack.dtb; fi; if test $board_name = BBG1; then setenv fdtfile am335x-bonegreen.dtb; fi; if test $board_name = A33515BB; then setenv fdtfile am335x-evm.dtb; fi; if test $board_name = A335X_SK; then setenv fdtfile dtbs/4.9.45-ti-r57/am335x-evmsk.dtb; fi; if test $board_name = A335_ICE; then setenv fdtfile am335x-icev2.dtb; fi; if test $fdtfile = undefined; then echo WARNING: Could not determine device tree to use; fi;'
=> saveenv
=> boot

That is all. Enjoy the Debian 9.1 on your AM335X EVM Start Kit.