undefined reference to `_start', undefined reference to `_data'

Hi, I'm trying to compile a project using Keil and GNUARM. Compiler compiles .c file but linker writes: Build target 'Target 1' assembling Startup.s... compiling Serial.c... compiling Blinky.c....
undefined reference to `_start', undefined reference to `_data'

Hi, I'm trying to compile a project using Keil and GNUARM. Compiler compiles .c file but linker writes: Build target 'Target 1' assembling Startup.s... compiling Serial.c... compiling Blinky.c....
HELP: GNUARM in KEIL ???

I opened C:\Keil\ARM\GNU\Examples\Blinky project and opened Project->manage->components..books dialog to set the GNUARM tools:select USE GNU compiler GNU-tool-prefix:arm-none-eabi- cynus Folder...
HELP: GNUARM in KEIL ???

I opened C:\Keil\ARM\GNU\Examples\Blinky project and opened Project->manage->components..books dialog to set the GNUARM tools:select USE GNU compiler GNU-tool-prefix:arm-none-eabi- cynus Folder...
Keil uVision Error L6218E: Undefined Symbol APBPrescTable (referred from stm32f4xx_hal_rcc.o)

I'm new to uVision for a University project and since trying to get my code to build on my PC at home I get this error with any code I try to compile. Anyone know any way to fix this? I've been racking...