<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body>
<p><br>
</p>
<div class="moz-cite-prefix">On 2020/8/18 下午4:55, Daniel P. Berrangé
wrote:<br>
</div>
<blockquote type="cite" cite="mid:20200818085527.GB20215@redhat.com">
<pre class="moz-quote-pre" wrap="">On Tue, Aug 18, 2020 at 11:24:30AM +0800, Jason Wang wrote:
</pre>
<blockquote type="cite" style="color: #000000;">
<pre class="moz-quote-pre" wrap="">On 2020/8/14 下午1:16, Yan Zhao wrote:
</pre>
<blockquote type="cite" style="color: #000000;">
<pre class="moz-quote-pre" wrap="">On Thu, Aug 13, 2020 at 12:24:50PM +0800, Jason Wang wrote:
</pre>
<blockquote type="cite" style="color: #000000;">
<pre class="moz-quote-pre" wrap="">On 2020/8/10 下午3:46, Yan Zhao wrote:
</pre>
<blockquote type="cite" style="color: #000000;">
<blockquote type="cite" style="color: #000000;">
<pre class="moz-quote-pre" wrap="">driver is it handled by?
</pre>
</blockquote>
<pre class="moz-quote-pre" wrap="">It looks that the devlink is for network device specific, and in
devlink.h, it says
include/uapi/linux/devlink.h - Network physical device Netlink
interface,
</pre>
</blockquote>
<pre class="moz-quote-pre" wrap="">Actually not, I think there used to have some discussion last year and the
conclusion is to remove this comment.
It supports IB and probably vDPA in the future.
</pre>
</blockquote>
<pre class="moz-quote-pre" wrap="">hmm... sorry, I didn't find the referred discussion. only below discussion
regarding to why to add devlink.
<a class="moz-txt-link-freetext" href="https://www.mail-archive.com/netdev@vger.kernel.org/msg95801.html" moz-do-not-send="true">https://www.mail-archive.com/netdev@vger.kernel.org/msg95801.html</a>
>This doesn't seem to be too much related to networking? Why can't something
>like this be in sysfs?
It is related to networking quite bit. There has been couple of
iteration of this, including sysfs and configfs implementations. There
has been a consensus reached that this should be done by netlink. I
believe netlink is really the best for this purpose. Sysfs is not a good
idea
</pre>
</blockquote>
<pre class="moz-quote-pre" wrap="">
See the discussion here:
<a class="moz-txt-link-freetext" href="https://patchwork.ozlabs.org/project/netdev/patch/20191115223355.1277139-1-jeffrey.t.kirsher@intel.com/" moz-do-not-send="true">https://patchwork.ozlabs.org/project/netdev/patch/20191115223355.1277139-1-jeffrey.t.kirsher@intel.com/</a>
</pre>
<blockquote type="cite" style="color: #000000;">
<pre class="moz-quote-pre" wrap=""><a class="moz-txt-link-freetext" href="https://www.mail-archive.com/netdev@vger.kernel.org/msg96102.html" moz-do-not-send="true">https://www.mail-archive.com/netdev@vger.kernel.org/msg96102.html</a>
>there is already a way to change eth/ib via
>echo 'eth' > /sys/bus/pci/drivers/mlx4_core/0000:02:00.0/mlx4_port1
>
>sounds like this is another way to achieve the same?
It is. However the current way is driver-specific, not correct.
For mlx5, we need the same, it cannot be done in this way. Do devlink is
the correct way to go.
<a class="moz-txt-link-freetext" href="https://lwn.net/Articles/674867/" moz-do-not-send="true">https://lwn.net/Articles/674867/</a>
There a is need for some userspace API that would allow to expose things
that are not directly related to any device class like net_device of
ib_device, but rather chip-wide/switch-ASIC-wide stuff.
Use cases:
1) get/set of port type (Ethernet/InfiniBand)
2) monitoring of hardware messages to and from chip
3) setting up port splitters - split port into multiple ones and squash again,
enables usage of splitter cable
4) setting up shared buffers - shared among multiple ports within one chip
we actually can also retrieve the same information through sysfs, .e.g
|- [path to device]
|--- migration
| |--- self
| | |---device_api
| | |---mdev_type
| | |---software_version
| | |---device_id
| | |---aggregator
| |--- compatible
| | |---device_api
| | |---mdev_type
| | |---software_version
| | |---device_id
| | |---aggregator
</pre>
</blockquote>
<pre class="moz-quote-pre" wrap="">Yes but:
- You need one file per attribute (one syscall for one attribute)
- Attribute is coupled with kobject
All of above seems unnecessary.
Another point, as we discussed in another thread, it's really hard to make
sure the above API work for all types of devices and frameworks. So having a
vendor specific API looks much better.
</pre>
</blockquote>
<pre class="moz-quote-pre" wrap="">From the POV of userspace mgmt apps doing device compat checking / migration,
we certainly do NOT want to use different vendor specific APIs. We want to
have an API that can be used / controlled in a standard manner across vendors.</pre>
</blockquote>
<p><br>
</p>
<p>Yes, but it could be hard. E.g vDPA will chose to use devlink
(there's a long debate on sysfs vs devlink). So if we go with
sysfs, at least two APIs needs to be supported ...</p>
<p>Thanks<br>
</p>
<p><br>
</p>
<blockquote type="cite" cite="mid:20200818085527.GB20215@redhat.com">
<pre class="moz-quote-pre" wrap="">
Regards,
Daniel</pre>
</blockquote>
</body>
</html>