Dear Supporters,
As previously descussion in https://community.arm.com/support-forums/f/architectures-and-processors-forum/57205/c2c-snp-address-width-diff-from-chi,
I wish to have your confirm about whether such a SNP address mapping relationship between C2C and CHI is correct or not:
For Req_Addr_Width = 52, SNP Addr width defined as Req_Addr_width – 3 = 49,
So the mapping between CHI <-> C2C would be:
CHI SNP -> C2C Snoop: C2C.Snoop.Addr[47:0] = CHI.SNP.Addr[48:1];
C2C Snoop -> CHI SNP: CHI.SNP.Addr[48:0] = {C2C.Snoop.Addr[47:0],1’b0];
So For Req_Addr_Width = 51, SNP Addr width defined as 51 – 3 = 48,
CHI SNP -> C2C Snoop: C2C.Snoop.Addr[47:0] = {1’b0,CHI.SNP.Addr[47:1]};
C2C Snoop -> CHI SNP: CHI.SNP.Addr[47:0] = {C2C.Snoop.Addr[46:0],1’b0];
Then For Req_Addr_Width = 50, SNP Addr width defined as 50 – 3 = 47,
CHI SNP -> C2C Snoop: C2C.Snoop.Addr[46:0] = {2’b0,CHI.SNP.Addr[46:1]};
C2C Snoop -> CHI SNP: CHI.SNP.Addr[46:0] = {C2C.Snoop.Addr[45:0],1’b0];
Best Regards
Hi Lingfan,
I've just responded in https://community.arm.com/support-forums/f/architectures-and-processors-forum/57205/c2c-snp-address-width-diff-from-chi, as I saw the question there first.
In isolation here though, your calculations look correct to me.
Kind regards,
Ben