Re: ifconfig eth0 mtu 2000: SIOCSIFMTU: Invalid argument

H. Peter Anvin (
3 Nov 1996 20:08:42 GMT

Followup to: <>
By author: "Michael L. Galbraith" <>
In newsgroup:
> Hello Everyone,
> I tried to adjust the mtu on an interface with the result:
> SIOCSIFMTU: Invalid argument

Care to specify what kernel version you're using?

> No interface (except lo) can be set to an mtu of over 1500 period.
> Did I miss something?
> Rules change on me? I used to be able to go up to 4096-header.

No, a bug was fixed. 1500 is the maximum MTU for Ethernet.

> It got a lot more interesting when Mr. Speedtypist here missed the
> "mtu" part. I inadvertently entered "ifconfig eth0 2000", with the
> following result:
> Nov 3 07:53:53 mikeg kernel: Unable to handle kernel paging request
> at virtual address f63a3336

Now this is a pretty serious kernel bug. "ifconfig eth0 2000" should
be interpreted as; I don't know why that barfed -- seems
pretty serious. On my system (2.0.20) it worked flawlessly; with the
expected result:

eth0 Link encap:10Mbps Ethernet HWaddr 00:A0:24:19:2F:71
inet addr: Bcast: Mask:
RX packets:343514 errors:0 dropped:0 overruns:0
TX packets:390530 errors:0 dropped:0 overruns:0
Interrupt:10 Base address:0x300

Ifconfig-ing back to the original address worked just fine; didn't
even lose my TCP connections (good thing, too, as I'm writing this
message over one of them.)


Not speaking for Transmeta in any shape, way, or form.