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Since it's USB you could do this all in > userland. There's no kernel subsystem that this would tie in to. It could end up in userspace, but there are reasons against it. Existing BMC userspace is written against a BMC-side IPMI character device. With CONFIG_USB_LSTP_IPMI_MSG_NUM disabled, read() and write() use the ssif_bmc layout; in the next version I plan to make that the default. The IPMI channel shares one USB interface with the GPIO, I2C and other channels. Those have kernel drivers, like other bridges, so userspace stays the same when a board is redesigned. An interface is bound to a kernel driver or to usbfs, not both, so the IPMI channel cannot move to userspace alone. Even if it could, serializing access and protocol state between kernel and userspace drivers would be inefficient and hard. Thanks, Adrian