I have an embedded device that runs Linux among other software licensed by the GNU GPL. The manufacturer never released any GPL code, and I plan to demand that from them tomorrow. My question is, do they just have to give me the code licensed under the GPL, or, given how one of my basic freedoms is to modify GPL-licensed software, do they have to give me a way to flash my modifications? (The device has a connection with my PC and if you have code implementing the protocol you can send commands to the Linux system over this connection.)
Note that I'm asking another question about this body of code here.