Linux emulation on FreeBSD AMD64

[Valery V.Chikalov]

Hi, list.

I have rather generic question.

I am exploring some Linux application (especially Oracle 9.0.1)
on FreeBSD starting from early RELENG-5.0.
During the time I have upgraded FreeBSD in order to 
5.1->5.5->6.0->6.1->6.2 and my Oracle database successfully survived
all this transitions.
Now being inspired the great performance improvements on multiprocessors 
configurations I am trying to switch to FreeBSD 7.0 version, moreover on 
AMD64 architecture. Must I expect some regression in support old Linux 
application here? Are some theoretical obstacles exists that linux 
application which successfully worked on FreeBSD from 5.0 up to 6.2
can not be running on 7.0 AMD64?

Of course I ask this questions because I was encountered some troubles 
already, when I am trying to start Oracle server I'm getting:

ORA-27122: unable to protect memory
Linux Error:13: Permission denied

the hint from Oracle:

oerr ORA 27122
27122, 00000, "unable to protect memory"
// *Cause: mprotect() call failed

Linux environment which I am using is the same from FreeBSD 5.0 days - rh7.

Of course Oracle is a black box and in any way is not intended to run in 
emulation environment, and possibly it is silly to hope to accomplish 
this quest. Nevertheless my question is where can I find information 
about what was changed in linux emulation environment from 6.2 to 7.0 or 
from i386 to AMD64? What are known limitations(regressions) of linux 
emulations in 7.0 AMD64?

Thank you.
Valery.