GENASSYM(1)

💅 GENASSYM(1) — like, the manual page, but make it make sense 🎀

okay bestie, so you know that one shell script that lives in the General Commands Manual section? yeah, that's genassym(1), and honestly she's lowkey the backbone of your kernel build. let's get into it ✨

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🌸 NAME 🌸

genassym — emit an assym.h file. that's it. that's the whole job. and she ATE. 💅

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🦋 SYNOPSIS 🦋

genassym [-c] [-f] C compiler invocation

like, you hand her a C compiler invocation and she does her thing. periodt.

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✨ DESCRIPTION ✨

so genassym is a shell script, and no cap, she's normally out here during the kernel build process doing the most important side quest ever: creating an assym.h file. 🫶

that file? it defines a bunch of cpp constants</> derived from the configuration info that genassym reads from stdin. the generated file gets used by kernel sources written in assembler so they can gain access to information — like structure offsets and sizes — that normally only the C compiler knows about. it's giving "translator between two friend groups who don't speak the same language." 😭

the arguments to genassym are usually of the form:

${CC} ${CFLAGS} ${CPPFLAGS}

where ${CC} is the C compiler used to compile the kernel, while ${CFLAGS} and ${CPPFLAGS} are flag arguments to the C compiler. iconic trio, honestly. 👑

so here's the vibe: the script creates a C source file from its input, then the C compiler gets called according to the script's arguments to compile this file. simple, clean, slay. ✨

normally, genassym instructs the C compiler to create an assembler source from the constructed C source. the resulting file is then processed to extract the info needed to create the assym.h file. and then — plot twist — the -c flag tells genassym to create slightly different code, generate an executable from this code, and run it. in BOTH cases the assym.h file is written to stdout. and the -f flag? that one tells genassym to create forth code. yes, forth. we contain multitudes. 🧚

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💖 DIAGNOSTICS 💖

the error messages are either self-explanatory, or generated by one of the programs called from the script. so if something goes off, it's probably not her fault, it's the friends she's calling. iykyk. 🙈

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🌈 SEE ALSO 🌈

• genassym.cf(5) — go read it bestie, it's the whole config file situation. 📖

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👑 HISTORY 👑

the genassym command appeared in NetBSD 1.3 as “genassym.sh” in /usr/src/sys/kern. she was lowkey underground at first. then she became a userland utility in NetBSD 4.0 and honestly? well deserved. main character energy from day one. ⭐

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ngl bestie, if you're debugging kernel build weirdness and assym.h is missing, check your ${CC}, ${CFLAGS}, and ${CPPFLAGS} first. the vibes will tell you. 💀

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k bye!! this page came from the Debian manual set, dated April 13, 2010 — so like, vintage but still serving. mwah 💋✨🎀