by support »
I have to admit that I haven't played around with switches. And indeed, running a plain lspci on my Linux machine reveals that the switches don't have any memory region allocated for themselves.
But at least theoretically, I could imagine that some switch vendor would like to set up a region for memory access. Suppose, for example, that the switch was used for sniffing TLP packets. In that case, the switch would also need to have its own registers and memory space. Well, it would make more sense to put the sniffer as an on-chip device hooked up on the switch, but I guess those who wrote the standard wanted to keep all options open.
And well, sometimes it's not so clear why certain features in a standard are there.
I have to admit that I haven't played around with switches. And indeed, running a plain lspci on my Linux machine reveals that the switches don't have any memory region allocated for themselves.
But at least theoretically, I could imagine that some switch vendor would like to set up a region for memory access. Suppose, for example, that the switch was used for sniffing TLP packets. In that case, the switch would also need to have its own registers and memory space. Well, it would make more sense to put the sniffer as an on-chip device hooked up on the switch, but I guess those who wrote the standard wanted to keep all options open.
And well, sometimes it's not so clear why certain features in a standard are there.