kernel_recvmsg(9)

💌 kernel_recvmsg — bestie edition

okay so this is a page from the Kernel API Manual (yes, the kernel kernel, we're in kernel space rn, no cap) and it's about kernel_recvmsg, which is literally how you receive a message from a socket when you're living that kernel-space life. sit down, grab a strawberry 🍓, let's get into it.

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✨ NAME ✨

kernel_recvmsg — receive a message from a socket, but make it kernel space 🫶

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✨ SYNOPSIS ✨

int kernel_recvmsg (struct socket *sock , struct msghdr *msg , struct
kvec *vec , size_t num , size_t size , int flags );

that's the whole signature, copy it exactly, do not freestyle it 💅

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✨ ARGUMENTS ✨

• sock — the socket you're receiving the message from. your source. your origin story. 🌸
• msg — the received message. this is where the good stuff lands. 💖
• vec — input scatter/gather array for the message data. the s/g icon of the group chat. ✨
• num — the size of that input s/g array. how many of them there are. 🎀
• size — number of bytes to read. yes, bytes. respect the units. 🦋
• flags — message flags, like MSG_DONTWAIT, etc... the "etc..." is doing a lot of heavy lifting here but that's what the page says, iykyk 😭

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✨ DESCRIPTION ✨

so here's the tea 🍵 — on return, the msg structure contains the scatter/gather array that you passed in through the vec argument. and not just as-is, bestie: the array gets modified so that it consists of the unfilled portion of the original array. it slims down. it's giving what's left over, and honestly? iconic. 👑

the returned value is the total number of bytes received, or an error. that's it. total bytes, or error. two outcomes, no in-between, periodt. 🔥

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✨ SEE ALSO ✨

the page also shouts out the kernel file ./net/socket.c and a whole friend group of related functions — go say hi to all of them, don't leave anyone on read 💜:

• move_addr_to_kernel(9)
• move_addr_to_user(9)
• sock_read_xattr(9)
• sock_alloc_file(9)
• sock_from_file(9)
• sockfd_lookup(9)
• sock_alloc(9)
• sock_release(9)
• sock_sendmsg(9)
• kernel_sendmsg(9)
• sock_recvmsg(9)
• sock_create_lite(9)
• __sock_create(9)
• sock_create(9)
• sock_create_kern(9)
• sock_register(9)
• sock_unregister(9)
• kernel_bind(9)
• kernel_listen(9)
• kernel_accept(9)
• kernel_connect(9)
• kernel_getsockname(9)
• kernel_getpeername(9)
• kernel_sock_shutdown(9)
• kernel_sock_ip_overhead(9)

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okay that's the whole page, you ate that 💅✨ mwah 🎀

this cutie lives in ./net and the page is dated October 2026, so like… future vibes, main character energy, kernel_recvmsg(9) forever 🌈💖🦋