Summary

In this chapter, we delved – in quite some depth – into the big topic of kernel memory management in a level of detail sufficient for a kernel module or device driver author like you; also, there’s more to come! A key piece of the puzzle – the VM split and how it’s achieved on various architectures running the Linux OS – served as a starting point.

We then moved into a deep examination of both regions of this split: first, user space (the user mode process VAS) and then the kernel VAS (or kernel segment). Here, we covered many details and tools/utilities on how to examine it (including via the quite powerful procmap utility). We built a demo kernel module that can literally generate a pretty complete memory map of the kernel and the calling process. User and kernel memory layout randomization technology ([K]ASLR) was also briefly discussed. We closed the chapter by looking at the physical organization of RAM within the Linux OS...