RE: [PATCH v2] bus/vmbus: add device_order field to rte_vmbus_dev

[Long Li <longli@microsoft.com>]

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Hi Vladimir,

Is there another way that you can determine the device probe order from your application? (like going through the /sys/class/uio devices)

Long

From: Vladimir Ratnikov <vratnikov@netgate.com>
Sent: Tuesday, June 25, 2024 4:50 AM
To: Stephen Hemminger <stephen@networkplumber.org>
Cc: Long Li <longli@microsoft.com>; dev@dpdk.org
Subject: Re: [PATCH v2] bus/vmbus: add device_order field to rte_vmbus_dev

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Thanks for review!

Regarding to
The patch only has the device_order field, but it is set but not used anywhere in the DPDK.
Unfortunately, It's not for DPDK usage, it's for DPDK based applications.
After some time of testing, if nothing's changed in the host OS(no new devices, no removed devices) - the device list is always the same with the same order.

On Tue, Jun 25, 2024 at 2:02 AM Stephen Hemminger <stephen@networkplumber.org<mailto:stephen@networkplumber.org>> wrote:
On Mon, 24 Jun 2024 11:15:21 +0000
Vladimir Ratnikov <vratnikov@netgate.com<mailto:vratnikov@netgate.com>> wrote:

> Field can be used to have static interface naming
> in DPDK based applications instead of uuid.
> RTE_FOREACH_DEV won't return the correct order of
> such devices due to vmbus_ignore_device in case of
> blocklisting/allowlisting. So device_order field
> will be helpful in that case.
>
> Signed-off-by: Vladimir Ratnikov <vratnikov@netgate.com<mailto:vratnikov@netgate.com>>
> ---

Not sure the order of device discovery is predictable.
The order of devices on vmbus is when they were reported by the host OS.
That is why Linux driver use other ways to have persistent naming.

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