Code Wrangling at its Best
Part IV — High-Voltage UPDI Activation and Recovery By the end of Part III, our Arduino Nano could do something genuinely useful. It could: That is already a practical programmer. But there remains an awkward problem. What happens if the microcontroller’s UPDI pin is no longer configured as UPDI? Or, on newer devices, what happens
Continue Reading “All You Ever Needed To Know About UPDI, And Then Some!”
Before reading the shell examples in this chapter, be explicit about the prompt transition: toyix> is the kernel monitor. ush> is the user shell. So when this chapter shows commands like: those commands must be typed inside the user shell after toyix> run shell. Chapter 39 made /programs/<name> usable as a launch target. That fixed
Continue Reading “Chapter 40 — Shell Job References with %1”
Before reading the shell examples in this chapter, be explicit about the prompt transition: toyix> is the kernel monitor. ush> is the user shell. So when this chapter shows commands like: those commands must be typed inside the user shell after toyix> run shell. Two other constraints still apply in this chapter: So cat README
Continue Reading “Chapter 39 — Path-Based Program Launching with /programs”
Before reading the shell examples in this chapter, be explicit about the prompt transition: toyix> is the kernel monitor. ush> is the user shell. So when this chapter shows commands like: those commands must be typed inside the user shell after toyix> run shell. In Chapter 37, Toyix gained its first real directory support at
Continue Reading “Chapter 38 — Turning /programs into a Real Directory”
In Chapter 36, Toyix gained file metadata: The shell could now do: Now we are ready for the next filesystem milestone: This chapter adds: After this chapter: For compatibility with the previous chapters, /programs will remain a regular text file for now: The root directory / becomes the first actual directory. 1. What this chapter
Continue Reading “Chapter 37 — Directories, SYS_READDIR, and ls”
Chapter 36 added SYS_STAT, which was the right filesystem step. But it also exposed a testing problem that has been growing for a while. Right now, Toyix testing is split across three awkward places: That worked while the system was small. It does not scale well now that Toyix has: The biggest smell is that
Continue Reading “Chapter 36.5 – A Testing Detour and a Real Smoke Harness”
In Chapter 34, Toyix gained its first tiny file layer: The shell could now do: But file descriptors were strictly forward-only. Once a file was read, its offset moved forward. There was no way to rewind, skip, or query position. This chapter adds: After this chapter, userland can do: And the shell gains a small
Continue Reading “Chapter 35 — SYS_SEEK and Rewindable File Descriptors”
By the end of Chapter 33, Toyix could launch child processes, inspect child state from the shell, and request cooperative termination: At this point, Toyix can: The next major subsystem is files. This chapter adds the first tiny filesystem path: After this chapter, the user shell can do: This is not a disk filesystem yet.
Continue Reading “Chapter 34 — First RAMFS and Core File APIs”
By the end of Chapter 32, Toyix could launch child processes, wait for them, and keep exited children around as zombies until the parent collected them. For this chapter, we also extend the shell and syscall ABI just enough to inspect child state from user mode: That gives the shell basic process ownership and job-state
Continue Reading “Chapter 33 — Process Termination and Kill Checks”
In Chapter 32, the user shell gained: That let a user process launch another user process: The flow worked: But the process model was too loose. Any process could wait for any PID. This chapter tightens that up. We will add: After this chapter, a child process belongs to the process that launched it: Then:
Continue Reading “Chapter 32 — Process Ownership, Waiting, and Job State”
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