[Gems-users] Can anyone help me to understand the trace?

[Xuehai Qian <xqian2@xxxxxxxx>]

Hi Everyone,
    I have a question related to Simics, it is not specifically about  
GEMS though. But in case anyone can explain it briefly, I appreciate  
the help.
> simics> stepi
> [cpu0 | 94060568239] pc:0xb7ffb1ae  instruction_callback
> SIMICS CYCLE: -428610385
> action=0
> inst: [        1] CPU  0 <l:0xb7ffb1ae> <cs:0xb7ffb1ae> <p: 
> 0x1fec11ae> c3                ret
> [cpu0 | 94060568239] pc:0xb7ffb1ae  operate_callback
> SIMICS CYCLE: -428610385
> [cpu0 | 94060568239] pc:0xb7ffb1ae  operate_snoop_callback
> SIMICS CYCLE: -428610385
> operate_snoop_callback:pc_laddr=0xb7ffb1ae
> data: [        1] CPU  0 <l:0xbffffa68> <ss:0xbffffa68> <p: 
> 0x1da13a68> Vani WB Read   4 bytes  0x0
> [cpu0] cs:0x00000000 <address not in TLB>
> simics>
My question is, what cause the cs to become 0? I think it is related  
to ss (stack) and return instruction, is it true that the return  
address on the stack is zero?? What does "Vani WB Read" mean? Thanks!
Xuehai