STRUCT PRINTK_MESSAGE(9)

💖 STRUCT PRINTK_MESSAGE(9) 💖

ok so this is a page from the Kernel API Manual — that's the manual name bestie, we're in the kernel docs now — and today's main character is struct printk_message, a whole container for a printk message that's already been prepped and is ready to go out into the world. ✨

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🌸 NAME 🌸

struct printk_message — literally a container for a prepared printk message. that's it, that's the vibe.

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🎀 SYNOPSIS 🎀

struct printk_message {
    struct printk_buffers   *pbufs;
    unsigned int            outbuf_len;
    u64 seq;
    unsigned long           dropped;
  #ifdef CONFIG_PRINTK_EXECUTION_CTX;
    int cpu;
    pid_t pid;
    char comm[TASK_COMM_LEN];
  #endif;
 };

like yes, it's giving struct, it's giving #ifdef, it's giving conditional members. we love a flexible icon. 💅

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🦋 Members 🦋

okay let's go member by member because every single one of them matters, no skips:

• pbufs — the printk buffers used to prepare the message. this is where the whole thing gets assembled, bestie. 🫶
• outbuf_len — the length of the prepared text in pbufs->outbuf that you're gonna output. 🎯 important detail: this does not count the terminator. and a value of 0 means there's nothing to output and this record should be skipped. zero = ghost, we move on.
• seq — the sequence number of the record used for pbufs->outbuf. it's the receipt, the tracking number, the iykyk. 🔥
• dropped — the number of dropped records from reading seq. yes, some got away 😭, this is how many.
• cpu — the CPU on which the message was generated. main character CPU energy 👑
• pid — the PID of the task that generated the message. we know exactly who did this.
• comm — the name of the task that generated the message. char comm[TASK_COMM_LEN] — the name, in all its task-name-sized glory. 💜

lowkey note: cpu, pid, and comm live inside that #ifdef CONFIG_PRINTK_EXECUTION_CTX; block up in the synopsis — so they're conditional members, not always along for the ride.

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🌈 SEE ALSO 🌈

go touch some related docs, they're all linked:

• Kernel file ./kernel/printk/internal.h — the file where the real ones live
• nbcon_kthread_wake(9)
• struct console_flush_type(9)
• struct printk_buffers(9)

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and that's the whole page, bestie — that's the tea, that's the lore. 🍓

this lil gem comes to you from the kernel source at ./kernel/printk, dated October 2026, and it's been struct printk_message(9) the whole time. periodt. 💅✨🧚