STRUCT GSM_CONFIG_EXT(9)

🌸 STRUCT GSM_CONFIG_EXT — n_gsm extended configuration parameters 🌸

okay bestie, this is struct gsm_config_ext(9) from the Kernel API Manual — yes it's a kernel thing, no it's not scary, come sit with me 💖

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✨ SYNOPSIS ✨

like, here's the whole shape of her, literally verbatim:

struct gsm_config_ext {
    __u32 keep_alive;
    __u32 wait_config;
    __u32 flags;
    __u32 reserved[5];
 };

that's it. that's the girl. five lines of pure struct energy 🎀

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👑 MEMBERS 👑

okay so each of these fields is a whole personality, let me introduce you:

• keep_alive — this is the control channel keep-alive, and the unit is 1/100th of a second. set it to 0 to disable it entirely (yes, zero means off, she's not doing the heartbeat thing anymore 💀).
• wait_config — the big question: do we wait for the DLCI config before opening the virtual link? that's literally what this field is asking. it's giving "are we patient or are we impulsive" energy 🙈
• flags — mux specific flags. mux. specific. flags. iykyk ✨
• reserved — for future use, and bestie listen to me: it must be initialized to zero. not "probably should", not "if you feel like it" — must. don't be the one who forgets this, i'm begging 🫶

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🌈 DESCRIPTION 🌈

so this structure gets used in combination with GSMIOC_GETCONF_EXT and GSMIOC_SETCONF_EXT to retrieve and set the extended parameters of an n_gsm ldisc. that's the whole job. get conf, set conf, extended edition 💅

and one thing that applies to all the timers here — no cap, every single one:

all timers are in units of 1/100th of a second</> . so like, do the math before you set a number, please, i'm asking nicely 😭

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🦋 SEE ALSO 🦋

go look at these next, they're all in the kernel file ./include/uapi/linux/gsmmux.h:

• struct gsm_config(9)
• struct gsm_netconfig(9)
• struct gsm_dlci_config(9)

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okay that's the whole page, periodt 💜 this gem lives in ./include/uapi/linux and the date on it is October 2026 — so yes she's from the future and she still wants you to zero out your reserved array. slay, go write some gsm code bestie 🌸🎀🦋