vio_h_cop_sync(9)

💫 vio_h_cop_sync(9) 💫

okay bestie, so this page lives in the Kernel API Manual and it's all about vio_h_cop_sync — say hi 👋

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✨ NAME ✨

vio_h_cop_sync — literally just perform a synchronous PFO co-processor operation. that's the whole vibe 🫶

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🌸 SYNOPSIS 🌸

int vio_h_cop_sync (struct vio_dev *vdev , struct vio_pfo_op *op );

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🎀 ARGUMENTS 🎀

okay so the original page is a little mysterious about these two, ngl:

• vdev — undescribed 🙈 (yes, really — that's all it says here)
• op — undescribed 🙈 (same energy, fr fr)

don't worry though, the description below comes in clutch and actually explains them 💅

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🦋 DESCRIPTION 🦋

let's break the params down properly, since the arguments section was being shy:

• vdev — pointer to a struct vio_dev for the device
• op — pointer to a struct vio_pfo_op for the operation parameters

so what does it do? it calls the hypervisor to synchronously perform the PFO operation described in op. slay ✨

now here's the part where you pay attention 👀 — in the case of a busy response from the hypervisor, the operation will be re-submitted indefinitely unless a non-zero timeout is specified or an error occurs. like, it will just keep going, no cap 💀 the timeout places a limit on when to stop re-submitting a operation, and heads up: the total time can be exceeded if an operation is in progress. so the timeout is a vibe check, not a hard guarantee 😭

also, if op->hcall_ret is not NULL, this will be set to the return from the last h_cop_op call — or it will be 0 if an error not involving the h_call was encountered. noted 🫡

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🔥 RETURN 🔥

here's the receipts, bestie — it returns:

• 0 on success 🎉
• -EINVAL if the h_call fails due to an invalid parameter
• -E2BIG if the h_call can not be performed synchronously
• -EBUSY if a timeout is specified and has elapsed
• -EACCES if the memory area for data/status has been rescinded
• -EPERM if a hardware fault has been indicated 💀

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🌈 SEE ALSO 🌈

Kernel file ./arch/powerpc/platforms/pseries/vio.c, plus these iconic neighbours:

• vio_cmo_alloc(9)
• vio_cmo_dealloc(9)
• vio_cmo_entitlement_update(9)
• vio_cmo_balance(9)
• vio_cmo_set_dev_desired(9)
• vio_cmo_bus_probe(9)
• vio_cmo_bus_remove(9)
• vio_cmo_bus_init(9)
• vio_match_device(9)
• vio_unregister_driver(9)
• vio_register_device_node(9)
• vio_bus_init(9)
• vio_get_attribute(9)
• vio_find_node(9)

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and that's the whole page, bestie, go forth and sync your co-processor 💜

sign-off szn: this one's from ./arch/powerpc/platforms/pseries, dated October 2026 — periodt. 👑