Bios Cache and CSL Cache

Hello,

I don't feel like an expert on caching so this may be some simple questions.

1.  I was wondering, when and why I should use BIOS cache and if there is an example? 

2.  I am using CSL caching.  When I ask it to invalid just the size of the variable, I get undefined behavoir.  Sometimes it works but if I readjust the memory map, then it might not.

CACHE_invL1d((void *)&glAssocationStartFlag, sizeof(unsigned int),CACHE_WAIT);

All the examples use 128, so I thought that value must just have been chosen as the default.  But I am thinking now, maybe not.  Why do they use 128?

CACHE_invL1d((void *)&glAssocationStartFlag, 128, CACHE_WAIT);

3.  What if I want to invalidate a variable (such as a struct) that is larger than 128, what should i do?

Thanks,

brandy