Re: [Qemu-devel] [PATCH v2] net: add mmsghdr struct check for L2TPV3

[Anton Ivanov (antivano)]

On 01/07/14 16:34, Peter Maydell wrote:
> On 1 July 2014 16:26, Anton Ivanov (antivano) <address@hidden> wrote:
>> On 01/07/14 16:14, Peter Maydell wrote:
>>> On 1 July 2014 16:06, Anton Ivanov (antivano) <address@hidden> wrote:
>>>> As far as general purpose linuxes, the relevant libc headers are present
>>>> in Ubuntul LTS 12.x and onwards, Debian 7.x, Fedora, and all other major
>>>> distros. I do not have a RHEL handy to check, but looking at release
>>>> notes that the kernel supporting recmmsg is in 6.0 in the first place
>>>> and so are the headers for glibc from certain point onwards.
>>> RHEL5 is still only 2.6.18 though (says wikipedia), so regardless of
>>> details of exactly which version this struct appeared in we still want
>>> to support compiling on a system which doesn't have it.
>>>
>>> (I'm planning to apply this patch to master for rc0; I'll fix up the
>>> commit message to quote a better version number.)
>> If we will support that far back, we need an emulation via recvmsg. I
>> will provide an incremental which does that.
> We don't need to support this optional feature on RHEL5, we
> just need not to die horribly trying to compile it when we're
> on an older system, that's all. This patch should be enough for
> this, right?

As a stop-gap -  yes.  An argument to configure which enables disables
the feature should be good for now.

I will try to supply a proper sendmms/recvmmsg configure test and
appropriate wrappers and patches by the end of the week so they can be
reused by anyone who wants to use sendmmsg/recvmmsg.

The performance difference these provide is quite significant so it will
be nice to port the legacy socket driver, etc to them too.

A.

>
> thanks
> -- PMM