Right, that's what I was saying. The statement "The kernel has limited stack space and isn't good at growing it." felt like a non sequitur when followed by "QNX

Right, that's what I was saying. The statement "The kernel has limited stack space and isn't good at growing it." felt like a non sequitur when followed by "QNX got this right. No strings in the kernel. Everything is either fixed-length or in user space. A privileged program in user space deals with filenames and such." Whether or not you use fixed space is orthogonal to whether you use VLA.