In computer world, PCIe has advanced in wonderful way. It has grown in laptop, desktop and server platform. PCIe protocol started with Gen1 speed (2.5 GT/s) having 8b/10b encoding/decoding with almost decades ago. PCIe applications were mainly in desktops at that time.
After few years, PCIe entered in Gen 2 speed (5 GT/s) having 8b/10b encoding/decoding. Applications extending from desktop to mobile and server platform. There are many advancements in terms of servers having SR_IOV and MR_IOV. SR_IOV means single root IO virtualization. It helps creating virtual functions requiring less number of physical functions. It has every physical functions having connected virtual functions. Virtual functions can be created on fly writing to SR_IOV configuration space. SR_IOV has brought revolution in server platforms. MR_IOV on other side have multiple root complex involved in it. It has base function and multiple virtual hierarchy involving one RC, one MR aware switch and one EP. MR_IOV has revolutionize the way server works by involving multiple virtual hierarchies.
There was an advancements in terms of SSD over PCIe in terms of NVMe. It means we can connect SSD over PCIe bus. It has one host connected with PCIe and other side connected with target. Faster SSD over faster PCIe bus has huge boost for Server platforms where faster accesses are required.
Then, there was enhancements in terms of SOP protocol means SCSI over PCIe. SCSI bus has controller connected to Root complex and target connected to Endpoint. It was great enhancements in PCIe domain. It became new norm in server market.
PCIe Gen3 came into existence. It has 128b/130b encoding and decoding. It has speed of 8 GT/s. Recently, PCIe Gen4 came into existence with having 16 GT/s. PCIe has covered market in server, desktop and mobile platform. There is many more to come in future for PCIe.
