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I figured out how to do what I was describing, but it was a bit counter-intuitive, so I'm posting the answer here for people who might hit this page when searching (tl:dr; at bottom). As far as I know, there is no blanket way to just filter out processes with a certain PID from ftrace as easily as it is to tell it to ONLY consider processes with a certain ...


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This Linux document gives the guidelines for adding a new system calls. Here are the key points from the it, related to our discussion When a new system call is added, it becomes a part of the kernel API, and has to be supported indefinitely. Creating a new system call is also a bigger responsibility as it involves creating test code, man pages, and a ...


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New system calls are added pretty rarely. Most new kernel functionality can be reached through a few general mechanisms: File descriptors are a very general feature for resource management. Custom actions on file descriptors happen through ioctl. Interactions are also possible through the proc filesystem and its variant sysfs for hardware- and driver-...


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Forget about real mode, that's just a detail of the x86 architecture and it's just there for compatibility with 1980's processors. The processor indeed has a flag that indicates the current privilege level. The details of that flag vary between processor types but to keep things simple just think of it as two settings: user and kernel. There are processor ...



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