The Qualcomm MSM Interface is a proprietary interface for interacting with Qualcomm baseband processors and is a replacement for the legacy cellular extensions of the Hayes command set.[1] With mobile chipsets, communication between the application processor and the baseband processor happens through shared memory. On PCs with data cards, QMI is exposed through USB.[2] [3]
In the Linux kernel, QMI can be used through two mutually exclusive drivers: GobiNet and qmi_wwan. These two drivers take completely different approaches to handle the protocol. GobiNet is a complex driver which implements within the kernel most of the core protocol logic, while qmi_wwan leaves all those tasks to user-space processes, and therefore keeping the kernel driver as small as possible.[4] There are several userspace implementations, such as uqmi on OpenWrt,[5] oFono[6] and libqmi[7]