svn commit: r246204 - head/sys/arm/include

[Juli Mallett]

On Fri, Feb 1, 2013 at 1:01 PM, Andre Oppermann <andre at freebsd.org> wrote:
> On 01.02.2013 21:23, Adrian Chadd wrote:
>>
>> .. before you make that assumption, please re-visit some the ..
>> lower-end integrated ethernet MACs in embedded chips.
>>
>> I don't know whether the Atheros stuff does (I think it does, but I
>> don't know under what conditions it's possible.)
>>
>> Maybe have it by default not return jumbo mbufs, and if a driver wants
>> jumbo mbufs it can explicitly ask for them.
>
>
> Jumbo frames do not see wide-spread use.  If they are used, then
> in data centre LAN environments and possibly also inter-datacenter.
> That is high performance environments.
>
> I seriously doubt that lower-end ethernet MACs you're referring to
> fit that bill.

These are silly generalizations, Andre.  I know of low-end systems in
jumbo frame environments.  I think Adrian's implication that Atheros
hardware can't handle doing scatter-gather into multiple buffers for
jumbo frames is probably an unlikely one, but if we have hardware that
requires jumbo mbufs, we should obviously keep supporting jumbo mbufs
to some extent.

Hypotheticals are somewhat irrelevant, but I find it surprising that
you're being so glib about breaking FreeBSD networking just because of
an idea you have about where jumbo frame use is appropriate and what
kinds of hardware should be connected to jumbo frame networks.