CWM for RK2928

download recovery.img [1]
adb kill-server
adb devices
adb push flash_image /dev/
adb push recovery.img /dev/
adb shell
chmod 755 /dev/flash_image
/dev/flash_image recovery /dev/recovery.img

or

sudo rkflashtool w 0x00012000 0x00010000 < ~/shared/T711/rom/rk2928-CWM/recovery.img

ignore message:  rkflashtool: fatal: premature end-of-file reached.

[1] http://files.androtab.info/rockchip/rk2928/20130425/RK2928GENERIC_CWM.zip