Down to the TLP: How PCI express devices talk (Part I)

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Down to the TLP: How PCI express devices talk (Part I)

Postby Guest » Thu Feb 13, 2014 4:00 pm

Hi, I know you posted this a while ago, but I was wondering why did you multiply by 4 the address in the sample write packet to get the physical address.

Thanks,

David
Guest
 

Re: Down to the TLP: How PCI express devices talk (Part I)

Postby support » Thu Feb 13, 2014 7:41 pm

Hi,

I did it, because that's the way to get the correct address.;)

Please note that the address field consists of bits [31:2] of DW2. Bits 1 and 0 of DW2 are reserved, and must be zero. So in effect, DW2 is the used bus address in that example, which is forced to be DW aligned.

But who knows, maybe bit 1 and 0 will be used for something else in future specs. So we consider bits [31:2] and multiply by four.

I hope this clarified this issue.

Regards,
Eli
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