Re: Network instability with jumbo frames on a G5

From: Kevin Bowling <>
Date: Tue, 15 Jun 2021 18:06:18 -0700
You are combining two things that I am skeptical of on FreeBSD on
their own, jumbo frames and bge(4) :)

If you just want the machine to work I'd say don't do that, but there
are some bugs to be fixed if you are up for it.

On Tue, May 18, 2021 at 9:22 PM Julio Merino <> wrote:
> Hi all,
> I'm trying to enable jumbo frames on my PowerMac G5 but I'm running into
> trouble. As soon as I type "ifconfig bge0 mtu 9000", the kernel prints this:
> [zone: mbuf_jumbo_9k] kern.ipc.nmbjumbo9 limit reached
> and the ifconfig command gets stuck. This obviously shouldn't be happening
> on a default configuration (right?).
> If I then bump kern.ipc.nmbjumbo9 (to ~40k, which is a bit bigger than the
> default ~32k), then the ifconfig command gets unstuck and the network
> becomes responsive again... to some extent. But whichever connection
> triggers a jumbo frame gets stuck: for example, managing the machine over
> SSH is impossible as any command that prints a lot of output quickly will
> cause the connection to stall and die.
> I've also tried with a smaller jumbo frame (4072) and observed the same
> issues.
> This is on a machine with 10GB of RAM and this adapter:
> bge0: <Broadcom BCM5714 B3, ASIC rev. 0x008003> mem
> 0xfa530000-0xfa53ffff,0xfa520000-0xfa52ffff irq 66 at device 4.0
> numa-domain 0 on pci3
> bge0: CHIP ID 0x00008003; ASIC REV 0x08; CHIP REV 0x80; PCI-X 33 MHz
> I'm now wondering if this could be related to the problems I was observing
> with USB drives as reported here:
> That said, the machine has been very stable otherwise...
> Any ideas?
> Thanks
> --
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Received on Wed Jun 16 2021 - 01:06:18 UTC

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