This trace follows the actual state transitions behind the companion A Process Is More Than a Program File. It describes a common execution path; implementation details can vary, so keep the contract separate from the mechanism.
Step 1: Create process execution state
A program file is a persistent description of code and data; a process is a running instance with execution state and an address space. The operating system gives a process a virtual view of memory, while hardware and the kernel translate that view to physical resources under protection rules.
Step 2: Map code and initial data
At launch, the loader maps executable code and data, creates a stack, prepares arguments and environment, and arranges runtime initialization. A function call changes registers and stack state inside the process. A system call crosses into privileged kernel code to request an operation the process cannot perform directly.
Step 3: Establish virtual addresses
A system call transfers control to privileged kernel code while preserving enough user state to return; ordinary application instructions do not directly perform the protected operation.
At this point, record the state that changed and check the invariant before advancing. If the operation repeats, make clear which values persist and which are recomputed.
Step 4: Cross the syscall boundary
Virtual addresses are not physical addresses and may not map to RAM until accessed. A process can have multiple threads sharing the same address space, so process isolation does not remove races within that process. Resource limits and file descriptors are part of execution context too.
Step 5: Resume or clean up execution
Explain how two processes can both use the same virtual address for different private data. What mechanism prevents one from freely reading the other’s memory?
The trace is complete when the result satisfies the stated contract. Compare this model with the concrete runtime or system you are studying before making a performance claim.