definitive way to set uname in jail?

[xorquewasp at googlemail.com]

It seems that the only way to set the output of uname in
a jail is to define environment variables.

Unfortunately, there doesn't seem to be a reliable way
to unconditionally set them (a process might do the
equivalent of 'env -i /bin/sh' and unset them, etc).

Apart from just patching the uname utility before I
copy it into a jail, is there really a good way to do
this?

I would love to just be able to set a sysctl and have
this work.

$ jls | grep i386
    29  127.1.0.13      7.2-i386-gnat_build           /usr/jails/7.2-i386-gnat_build
$ sudo jexec 29 csh
FreeBSD 7.2-i386-gnat_build 8.0-RELEASE FreeBSD 8.0-RELEASE #0: Sat Nov 21 15:02:08 UTC 2009     root at mason.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC  amd64

Regards,
xw