Solaris

Hi, I am a newbie to solaris and i have some questions on shared memory, Oracle in Solaris

My Questions might seem different, however please do read and try to answer. Thanks in advance.

1) if a solaris server has say 40gb of Ram, what would be the maximum size of a shared memory segment in this machine?
I know that if the server has 40GB. then max shared memory size is 10GB i.e. one fourth of ram, however not sure

2) What is the maximum size of a shared memory segment in solaris that a root user can define.
+ i know that its some where near 14 GB not very sure +

3) Assume i have created a user X and i allocated say 10GB limit for this user for shared memory.
I login to solaris using X and now, can i increase the size of the shared memory that this user can use?

I have a situation, where the root user, created a user named DBA and the root user allocated some 15gb for this DBA user as the max SHM limit.
Now the DBA user has set the max limit for shared memory as 1TB, which is causing hell of problems in the system.
* I am Not very sure on the concept. I am new to this product and facing this problem. please advice.*

check out this link ..
Byte Reader: Install Oracle 10g in Solaris 10 x86 (Part 1)