sparc v9 global register usage

[raymond.meyer%rambler.ru@localhost]

What ABI does NetBSD follow on sparc v9 in regard to global registers,
i.e. is it different to the following:

http://developers.sun.com/solaris/articles/sparcv9abi.html

Say I have the following code:

1. set global reg G to memory address;
2. call library function;
3. use global reg G to load data at that memory address;

At line 3 I get segmentation fault, I assume that's because when I call
library function at line 2, it resets that global register to some
other value.

So, what global registers can I use which are not volatile across
function/library calls?