uart_try_toggle_sysrq(9)

💫 uart_try_toggle_sysrq(9) 💫

okay so bestie, we're in the Kernel API Manual today and the function we're stanning is uart_try_toggle_sysrq — a little icon that literally turns on SysRq from the serial line. yes, from the serial line. the way that serial consoles keep serving looks ✨

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🌸 NAME 🌸

uart_try_toggle_sysrq — enables SysRq from serial line. that's it, that's the whole vibe. 🎀

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🦋 SYNOPSIS 🦋

bool uart_try_toggle_sysrq (struct uart_port *port , u8 ch );

look at her. so clean. so composed. 💅

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🍓 ARGUMENTS 🍓

• port — the uart_port structure where the char(s) after BREAK were met. like, this is the port that just witnessed the BREAK moment, and we're checking what came next, iykyk. 🔥
• ch — the new character in the sequence after the received BREAK. main character energy fr fr, because this one char decides whether we toggle or not. 👑

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🧚 DESCRIPTION 🧚

so here's the tea 🫖: this function enables magic SysRq when the required sequence is met on port. the required sequence in question is defined by CONFIG_MAGIC_SYSRQ_SERIAL_SEQUENCE — she's in the config, go look, it's giving prerequisites. ⭐

basically you send a BREAK, then a sequence of chars, and if everything slays in the right order, boom, SysRq gets toggled. no cap. 🌈

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💜 RETURN 💜

• returns false if ch is out of the enabling sequence — meaning nope, not it, this char should be handled some other way, don't @ her.
• returns true if ch was consumed. ate it right up, no crumbs. 🔥

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🎀 SEE ALSO 🎀

kernel file ./drivers/tty/serial/serial_core.c — that's the home turf bestie, go visit her 💖 — plus the whole friend group:

• uart_write_wakeup(9)
• uart_update_timeout(9)
• uart_get_baud_rate(9)
• uart_get_divisor(9)
• uart_get_lsr_info(9)
• uart_console_write(9)
• uart_parse_earlycon(9)
• uart_parse_options(9)
• uart_set_options(9)
• uart_change_pm(9)
• uart_register_driver(9)
• uart_unregister_driver(9)
• serial_core_add_one_port(9)
• serial_core_remove_one_port(9)
• uart_match_port(9)
• uart_handle_dcd_change(9)
• uart_handle_cts_change(9)
• uart_insert_char(9)
• uart_get_rs485_mode(9)

like, the entire serial_core squad showed up to the group chat. obsessed. 😭🫶

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warning bestie: the whole magic-SysRq-over-serial thing depends on that CONFIG_MAGIC_SYSRQ_SERIAL_SEQUENCE config being set up the way you want. check your config before you go toggling things, mwah 💅

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okay that's the page!! sourced straight from ./drivers/tty/serial, dropped in October 2026, signed uart_try_toggle_sysrq(9) — mwah, ily, go read your kernel docs 🌸💖🦋