[ofa-general] Re: [PATCH v4 14/14] QLogic VNIC: sysfs Documentation
Patrick McHardy
kaber at trash.net
Mon Jun 16 13:39:19 PDT 2008
Amar Mudrankit wrote:
>>> I was looking at latest release of iproute2, in which I could not
>>> locate fill_xstats. Can you help me to locate this?
>> ->fill_xstats is in the kernel, in iproute its ->print_xstats.
>
> I was looking at kernel code net/8021q/vlan_netlink.c on which I have
> following queries:
>
> a. Is it a correct file in kernel I m referring to?
Yes.
> b. vlan_fill_info is a function to send parameters back to user
> level. What is the role of skb as an argument to function? Is some
> network operation expected?
netlink is a (local) networking protocol, this is the message
sent to userspace.
> c. How exactly the kernel API ops->get_size comes into play? I guess
> user prog should first get the size of parameters that will be
> returned by driver before calling ops->fill_info.
No, its used internally for skb allocation. It should return
the size of all encapsulated netlink attributes that will be
dumped by ->fill_info (in most cases, just a constant value).
> d. Can somebody briefly introduce struct nlattr? It looks like all
> parameters flow through this structure.
Not much to say about it, nla_type contains the numerical
attribute type, nla_len the length without padding. Data
follows the attribute, followed by padding to a multiple
of four. The netlink construction functions and macros
from include/net/netlink.h take care of all of this for
you.
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