vhost_get_vq_desc_n(9)

💖 vhost_get_vq_desc_n(9) — the group chat version 💖

okay so bestie, today we're doing vhost_get_vq_desc_n from the <cyan>vhost_get_vq_desc_n(9)</cyan> kernel API manual — yes that's the manpage name, and yes it's a mouthful, but she's iconic and she's about to hand you your next descriptor chain 🎀

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✨ NAME ✨

vhost_get_vq_desc_n — fetch the next available descriptor chain and build iovecs. literally her whole personality 💅

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🦋 SYNOPSIS 🦋

int vhost_get_vq_desc_n (struct vhost_virtqueue *vq , struct iovec iov[]
, unsigned int iov_size , unsigned int *out_num , unsigned int *in_num ,
struct vhost_log *log , unsigned int *log_num , unsigned int *ndesc );

no cap, that's the whole signature. keep it close 🫶

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🌸 ARGUMENTS 🌸

girl, there are a LOT of them, but each one is serving a purpose:

• vq — the target virtqueue. the main character, fr fr 👑
• iov — the array that receives the scatter/gather segments. she collects the pieces ✨
• iov_size — capacity of iov in elements. don't overfill her, bestie 🌈
• out_num — the number of output segments
• in_num — the number of input segments
• log — optional array to record addr/len for each writable segment; NULL if unused. optional, like your third coffee ☕
• log_num — optional output; number of entries written to log when provided
• ndesc — optional output; number of descriptors consumed from the available ring (useful for rollback via vhost_discard_vq_desc). this one's lowkey the receipts 🧾

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💜 DESCRIPTION 💜

So what does she actually do? She extracts one available descriptor chain from vq and translates guest addresses into host iovecs. it's giving translator-girlie, it's giving bridge between two worlds 🌉

On success, she advances vq->last_avail_idx by 1 and vq->next_avail_head by the number of descriptors consumed (also stored via ndesc when non-NULL).

careful bestie — those indices move on success, and that's exactly why ndesc exists. if you need to roll back, vhost_discard_vq_desc is your girl 🙈

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🔥 RETURN 🔥

the vibe check results, in order:

• head index in [0, vq->num) on success 🎉
• vq->num if no descriptor is currently available 😭 (yes, that's the "nothing rn" signal — not an error!)
• negative errno on failure 💀

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🎀 SEE ALSO 🎀

Kernel file ./drivers/vhost/vhost.c — go read __vhost_worker_flush(9) and vhost_discard_vq_desc(9), they're the supporting cast and they ATE ⭐

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okay that's the whole page, bestie. mwah 💋

this lil masterpiece lives in ./drivers/vhost, dated October 2026 — that's the source and the version-date, noted with love so you never have to squint at a footer again 🧚💖✨