No IPFW binary compat across versions ?

[Arnaud Lacombe]

Hi,

On Mon, Sep 5, 2011 at 8:45 PM, Doug Barton <dougb at freebsd.org> wrote:
> On 09/05/2011 17:18, Arnaud Lacombe wrote:
>> From my point of view, I should be able to run a FreeBSD 9.0 kernel
>> (when released) on top of a FreeBSD 5 userland without such issues.
>
> Unfortunately your expectation is completely unrealistic.
>
Completely unrealistic ? Seriously, you've got to be kidding me ?

I just downloaded a 4 (_four_) years old OpenWRT image, built the
latest Linux kernel in development and it worked just fine. netstat(8)
works just fine, I can pick a random iptables tutorial on the net, and
it still works fine. Those binaries are 4 years old and still work, oh
and I can go back at will to the original 2.6.19 without issue.

Now, let's see FreeBSD. Beside the issues included in that thread, the
latest development are the following: if you boot a FreeBSD 8-STABLE
kernel, with a 7.4 userland, then reboot on a 7-STABLE kernel, the
system will no longer boot, even in single user. Why ? because
fsck_ufs(8) crashes on a SIGFPE. I'll avoid commenting further.

Anyway, now I'll be obliged to re-install (well, find the motivation
first) if I want to be able to track down the mbuf corruption in
FreeBSD 7-STABLE I already reported.

Happy bikeshed coloring,

 - Arnaud

> We do our best
> to maintain backward compatibility but sometimes improvements require
> breaking the KBI/ABI.
>
> Also, we have never supported running a kernel from RELENG_N on anything
> older than the latest version of RELENG_{N-1}.
>
>
> hth,
>
> Doug
>
> --
>
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>