rpc_max_payload(9)

💅 rpc_max_payload(9) — a Kernel API Manual moment ✨

okay so bestie, we're in the kernel API manual today (that's the manual name, iykyk 🎀) and the page is all about rpc_max_payload — and no cap, it's a tiny one, so hydrate and let's go 🧚

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🌸 NAME 🌸

rpc_max_payload — get the maximum payload size for a transport, in bytes 💖 like, literally, the biggest chunk of payload a transport can carry, measured in bytes. that's the whole vibe check.

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✨ SYNOPSIS ✨

size_t rpc_max_payload (struct rpc_clnt *clnt );

it's giving "one function, one argument, one size_t back" and honestly? iconic. 👑

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🦋 ARGUMENTS 🦋

• clnt — the RPC client you're querying 🔍 that's the one you're asking about, bestie. RPC client to query. periodt.

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💜 DESCRIPTION 💜

okay so the answer depends on what kind of transport you're on, and it's a whole two-for-two situation:

• stream transports 🌀 — the value is one RPC record fragment (see RFC 1831), because we don't support multi-record requests yet. not yet!! like, someday maybe, but today? one fragment. that's the rule. 🙈
• datagram transports 📨 — the value is the size of an IP packet, minus the IP, UDP, and RPC header sizes. so it's the packet size after everybody's taken their cut. math, but make it networking 💅

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⭐ SEE ALSO ⭐

Kernel file ./net/sunrpc/clnt.c — go read the source if you're feeling main character energy 👑

and then the whole friend group, fr fr:

• rpc_create(9)
• rpc_clone_client(9)
• rpc_clone_client_set_auth(9)
• rpc_switch_client_transport(9)
• rpc_clnt_iterate_for_each_xprt(9)
• rpc_cancel_tasks(9)
• rpc_hold_client(9)
• rpc_release_client(9)
• rpc_bind_new_program(9)
• rpc_run_task(9)
• rpc_call_sync(9)
• rpc_call_async(9)
• rpc_run_bc_task(9)
• rpc_prepare_reply_pages(9)
• rpc_peeraddr(9)
• rpc_peeraddr2str(9)
• rpc_localaddr(9)
• rpc_net_ns(9)
• rpc_max_bc_payload(9)
• rpc_force_rebind(9)
• rpc_clnt_test_and_add_xprt(9)
• rpc_clnt_setup_test_and_add_xprt(9)
• rpc_clnt_add_xprt(9)

like, that's the whole group chat 😭 and yes rpc_max_bc_payload(9) is the sibling page, they're twins but not identical, don't mix them up 💀

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and that's the page!! 🫶 shoutout to ./net/sunrpc for bringing us together, timestamped October 2026, still rocking the rpc_max_payload(9) name — slay, ate, no crumbs left 💖✨🎀