Porting an OS into STM32VL

Question

[...] so that I can interface a touch screen and later make this project into MP3 player or Internet Radio.

Neither of those things necessarily require an OS, and while an OS may make development easier there is little in an OS that will "do that for you". Touchscreen support is likely to be entirely down to you, though there are a number of GUI libraries for small screens and microcontrollers (few are free however).

A typical RTOS is provided as a library statically linked to your application code. It provides services for task scheduling, timing, synchronisation, and messaging. Some RTOS may provide higher level "middleware" such as a network stack, USB support, and a filesystem, but you might also use third-party libraries for those.

However to answer your question directly, certainly you can run an RTOS. Any Cortex-M3 supporting RTOS will run, because the Cortex-M3 core provides all the critical support for an RTOS (NVIC, SYSCLK), there is very little "porting" to do as such to get a basic RTOS scheduler working.

What you should certainly investigate other than an RTOS is ST's STM32 Standard Peripheral Library which provides support for all the peripherals and GPIO available on your device.

Here's a list of open-source RTOS libraries with STM32 ports.

FreeRTOS's site has a page specifically for the STM32 discovery.

For C programming Cortex-M (the core used in STM32) is ideal; it supports C execution from reset and interrupt service routines can be coded directly in C with no assembler glue or special compiler extensions whatsoever.

And sure if you are smart, two months is plenty of time, but the OS is not the biggest issue - support for networking and a file system is likely to be key in the applications you have suggested, and integrating those with your RTOS is critical.