Relationship between H/W ring and S/W ring

[Gyumin <hkm73560-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

Hi

I`m reading the ixgbe code especially about H/W ring and S/W ring. Is 
the relationship between H/W ring and S/W ring one-to-one mapping?
As far as I know, H/W ring size is determined in the code(hard coded) 
while S/W ring size is determined in port configuration time.
In the ixgbe_rx_alloc_bufs function, H/W ring header address and packet 
address indicate the DMA address of S/W ring's mbuf. I understand it 
means that the relationship between the H/W ring and S/W ring is 
one-to-one mapping. For example, if the size of H/W ring is greater than 
the size of  S/W ring then some portion of H/W ring is unused. Is it 
correct?

Thanks