关于pcie设备中会让选择是几个通道,可以选择的有x1,x2,x4…x32等。这些可选的项似乎都是2的幂次方,为什么不可以选择其他的?
通过查看pice规范的手册可以知道,通道的数量即Lane的个数值是可以是任意值,主要是看设备的支持情况。下面附上手册中的原文:
Lanes – A Link must support at least one Lane – each Lane represents a set of differential signal pairs (one pair for transmission, one pair for reception). To scale bandwidth, a Link may aggregate multiple Lanes denoted by xN where N may be any of the supported Link widths. A x8 Link operating at the 2.5 GT/s data rate represents an aggregate bandwidth of 20 Gigabits/second of raw bandwidth in each direction. This specification describes operations for x1, x2, x4, x8, x12, x16, and x32 Lane widths.
手册中提到了这个值可以任意写,但是手册只描述了 x1, x2, x4, x8, x12, x16, and x32这几种情况,因此可能大多数的设备商就按照这个通道进行设置了。(关于这一点本人不是很确定,希望大家多多交流)
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