Code Wrangling at its Best
In Chapter 27, we added a second user program: That proved the program registry can handle more than one embedded ELF. But the Makefile now has duplicated build rules: That will not scale. This chapter cleans up the user-program build system so adding a new user program is mostly: and then adding: The build system
Continue Reading “Chapter 28 — Pattern-Based User Program Build System”
In Chapter 26, we added: That gave us a real background process path. But our only user program, demo, waits for terminal input: That makes it awkward for runbg, because a background process can compete with the monitor for keyboard input. This chapter adds a second embedded user program: counter does not read from stdin.
Continue Reading “Chapter 27 — A Second User Program for Safe Background Execution”
In Chapter 25, the monitor gained an embedded program registry and a foreground run command: That gave us an exec-like path, but only in foreground mode: This chapter adds the next process-management layer: After this chapter, the monitor will support: The kernel still does not have job control, signals, or a filesystem, but it now
Continue Reading “Chapter 26 — Process Table, ps, runbg, and wait PID”
In Chapter 23, we crossed another major boundary: But the user program still started like this: That is not how we want user programs to look long-term. This chapter adds a real initial user stack with: Then crt0.S will pass those arguments to: This moves us closer to a normal process startup model. ELF process
Continue Reading “Chapter 24 — User argc / argv and a Real Initial Stack”
In Chapter 22, the kernel gained a first ELF32 loader. That was a big step, but our test ELF was still built by hand inside process.c: This chapter removes that artificial piece. We will add a tiny userland build pipeline: GNU objcopy is specifically designed to copy and transform object files between formats; we will
Continue Reading “Chapter 23 — Building a Real User C Program and Embedding Its ELF”
In Chapter 21, we completed the process lifecycle: Now we can replace the temporary TOYEXE format with the first real executable-loader milestone: ELF32. ELF is the Executable and Linkable Format used by many Unix-like systems. The ELF specification defines the file header, program header table, and how loadable segments describe a process image; the generic
Continue Reading “Chapter 22 — First ELF32 Loader Milestone”
In Chapter 20, we added the TOYEXE loader: But there is still a lifecycle problem. The process can exit, but we are not yet reclaiming everything it owns. Right now this leaks: This chapter closes that loop. After this chapter, the process lifecycle becomes: The milestone output will look like: 1. What this chapter adds
Continue Reading “Chapter 21 — Process Teardown and Address-Space Cleanup”
A Beginners Guide Introduction Communication protocols are vital for enabling embedded devices to interact effectively. Three prominent protocols, Modbus, Standard Commands for Programmable Instruments (SCPI), and General Purpose Interface Bus (GPIB), stand out due to their widespread adoption in various industrial and testing environments. Recently, I had the opportunity to work on an embedded project
Building robust, fault-tolerant applications is crucial in today’s fast-paced digital landscape. This comprehensive article explores the essential properties of fault-tolerant applications, including isolation, concurrency, failure detection, live code upgrade, stable storage, and more. Learn about techniques used in critical environments like aerospace, and discover how organizations like NASA handle fault tolerance and remote code upgrades.
Continue Reading “Building Robust Systems: The Properties of Fault-Tolerant Applications”
Dive into the world of distributed systems with our comprehensive guide on the Chord algorithm. Understand its applications, advantages, and limitations. Explore a Python implementation, gaining hands-on insights into this powerful distributed hash table protocol.
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