Date: Mon, 1 Jun 2026 21:44:14 +0000 From: John F Carr <jfc@MIT.EDU> To: "freebsd-drivers@freebsd.org" <freebsd-drivers@FreeBSD.org> Subject: Providing struct device for Linux USB drivers Message-ID: <46754738-2FFD-4799-AF68-0F12E1D96C1A@mit.edu>
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I am trying to get the USB part of the rtw89 driver working. This driver uses the Linux 2.6.24 USB interface, which is newer than LinuxKPI supports. The rtw89 driver expects struct usb_interface to contain a field struct device dev; A struct device is 256 bytes, much larger than the existing 80 byte struct usb_interface. Is that too much bloat? The number of these structures is not very large. Alternatively, I could add a pointer instead of a value, struct device *dev; The struct device object would be allocated in usb_linux_create_usb_device and freed and nulled in usb_linux_detach. With this approach the KPI is not purely source compatible. The driver change is as simple as removing an "&". For PCI, LinuxKPI provides a struct device by interposing a struct pci_dev between the FreeBSD structure and the Linux driver. For USB the structure name is expected to be "usb_interface", which is already used. Any thoughts? John Carrhome | help
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