setup_earlycon(9)

🌸 NAME 🌸

setup_earlycon — match and register earlycon console, bestie. This is the setup_earlycon(9) page from the Kernel API Manual, and we are gonna make it make sense 💅

✨ SYNOPSIS ✨

int setup_earlycon (char *buf );

🎀 ARGUMENTS 🎀

• buf — the earlycon param string. That's the little string doing all the matchmaking, no cap.

💅 DESCRIPTION 💅

So this function registers the earlycon console that matches the earlycon specified in the param string buf. The acceptable param strings are totally giving these forms:

<name>,io|mmio|mmio32|mmio32be,<addr>,<options>
<name>,0x<addr>,<options>
<name>,<options>
<name>

Only for the third form — yep, the <name>,<options> one — does the earlycon setup method receive the <options> string in the 'options' parameter. All the other forms set that parameter to NULL. That's the rule, bestie, don't forget it 🫶

It returns 0 if an attempt to register the earlycon was made; otherwise it gives you a negative error code. So 0 is literally "an attempt was made" — that's the whole return vibe 😌

🦋 SEE ALSO 🦋

• Kernel file ./drivers/tty/serial/earlycon.c — go read it, it's the main character 🔥

mwah 💋 this page is sourced from ./drivers/tty/serial, dated October 2026, and it's the setup_earlycon(9) entry in the Kernel API Manual. bye bestie, slay your earlycon setup 🌈✨