On Wed, Aug 29, 2018 at 7:12 PM, Dan Gora <d...@adax.com> wrote:
> On Wed, Aug 29, 2018 at 7:00 PM, Stephen Hemminger
> <step...@networkplumber.org> wrote:
>>> >> Add a new API function to KNI, rte_kni_update_link() to allow DPDK
>>> >> applications to update the link state for the KNI network interfaces
>>> >> in the linux kernel.
>>> >>
>>> >> Note that the default carrier state is set to off when the interface
>>> >> is opened.
>>> >>
>>> >> Signed-off-by: Dan Gora <d...@adax.com>
>>> >
>>> > Do you really need a special ioctl for this?
>>> > There is already ability to set link state via sysfs or netlink.
>>>
>>> I think yes.. AFAIK sysfs does not constitute a stable API;
>>
>> It is a stable API on Linux.
>
Actually this does not seem to be completely true...
>From Documentation/admin-guide/sysfs-rules.rst:
Rules on how to access information in sysfs
===========================================
The kernel-exported sysfs exports internal kernel implementation details
and depends on internal kernel structures and layout. It is agreed upon
by the kernel developers that the Linux kernel does not provide a stable
internal API. Therefore, there are aspects of the sysfs interface that
may not be stable across kernel releases.
<snip>
- devices are only "devices"
There is no such thing like class-, bus-, physical devices,
interfaces, and such that you can rely on in userspace. Everything is
just simply a "device". Class-, bus-, physical, ... types are just
kernel implementation details which should not be expected by
applications that look for devices in sysfs.
The properties of a device are:
- devpath (``/devices/pci0000:00/0000:00:1d.1/usb2/2-2/2-2:1.0``)
<snip>
- kernel name (``sda``, ``tty``, ``0000:00:1f.2``, ...)
<snip>
- subsystem (``block``, ``tty``, ``pci``, ...)
<snip>
- driver (``tg3``, ``ata_piix``, ``uhci_hcd``)
<snip>
- attributes
<snip>
Everything else is just a kernel driver-core implementation detail
that should not be assumed to be stable across kernel releases.
