ibmvmc_add_buffer(9)

💅 ibmvmc_add_buffer — like, the Kernel API Manual (section 9) girlies know ✨

okay so bestie, gather round, because this one is a kernel API page from the good people over in ./drivers/misc and we are gonna get you fluent, no cap 🫶

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🌸 NAME 🌸

ibmvmc_add_buffer — literally just Add Buffer. that's the whole vibe. iconic, concise, slay ✨

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🦋 SYNOPSIS 🦋

int ibmvmc_add_buffer (struct crq_server_adapter *adapter , struct
ibmvmc_crq_msg *crq );

she takes two things and returns an int, periodt.

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🎀 ARGUMENTS 🎀

• adapter — a crq_server_adapter struct. that's her. that's the struct 💅
• crq — an ibmvmc_crq_msg struct. the message itself, bestie.

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💖 DESCRIPTION 💖

so the whole point of this message? it transfers a buffer from hypervisor ownership to management partition ownership. like a handoff. a baton pass. very main character energy 🤝

the LIOBA comes from the virtual TCE table associated with the hypervisor side of the VMC device, and it points to a buffer of size MTU — and that MTU was established back in the capabilities exchange, so it's already settled, don't come for her 🙈

now here's the typical flow for adding buffers, in order, because we love a numbered list:

1. a new management application connection is opened by the management partition.
2. the hypervisor assigns new buffers for the traffic associated with that connection.
3. the hypervisor sends VMC Add Buffer messages to the management partition, letting it know about the new buffers.
4. the hypervisor sends an HMC protocol message (to the management application) notifying it of the new buffers. this is the part that tells the application "hey girl, you've got buffers available for sending HMC commands" 💅

like the way it's just four steps and each one eats?? we love a clean sequence 🔥

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⭐ RETURN ⭐

• 0 — Success 🎉
• Non-zero — Failure 😭 (sad but true)

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💜 SEE ALSO 💜

okay this section is long, but we do not skip. we never skip. every single one of these is coming with us:

the kernel file ./drivers/misc/ibmvmc.c and then, in order:

h_request_vmc(9), ibmvmc_handle_event(9), ibmvmc_release_crq_queue(9), ibmvmc_reset_crq_queue(9), crq_queue_next_crq(9), ibmvmc_send_crq(9), alloc_dma_buffer(9), free_dma_buffer(9), ibmvmc_get_valid_hmc_buffer(9), ibmvmc_get_free_hmc_buffer(9), ibmvmc_free_hmc_buffer(9), ibmvmc_count_hmc_buffers(9), ibmvmc_get_free_hmc(9), ibmvmc_return_hmc(9), ibmvmc_send_open(9), ibmvmc_send_close(9), ibmvmc_send_capabilities(9), ibmvmc_send_add_buffer_resp(9), ibmvmc_send_rem_buffer_resp(9), ibmvmc_send_msg(9), ibmvmc_open(9), ibmvmc_close(9), ibmvmc_read(9), ibmvmc_poll(9), ibmvmc_write(9), ibmvmc_setup_hmc(9), ibmvmc_ioctl_sethmcid(9), ibmvmc_ioctl_query(9), ibmvmc_ioctl_requestvmc(9), ibmvmc_ioctl(9), ibmvmc_rem_buffer(9), ibmvmc_process_capabilities(9), ibmvmc_validate_hmc_session(9), ibmvmc_reset(9), ibmvmc_reset_task(9), ibmvmc_process_open_resp(9), ibmvmc_process_close_resp(9), ibmvmc_crq_process(9), ibmvmc_handle_crq_init(9), ibmvmc_handle_crq(9), ibmvmc_init_crq_queue(9)

like. that's the whole friend group. everyone showed up. 🌈

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ngl bestie, if you're poking at VMC stuff in the kernel, read the whole list. iykyk 🧚

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and that's the page! this one lives in ./drivers/misc and it's dated October 2026 — so go forth, add those buffers, and remember: hypervisor ownership → management partition ownership. mwah 💋 slay! 🍓