Hi, Greg Kroah-Hartman <gre...@linuxfoundation.org> writes: >> > xHCI compatible USB host controllers(i.e. super-speed USB3 controllers) >> > can be implemented with the Debug Capability(DbC). It presents a debug >> > device which is fully compliant with the USB framework and provides the >> > equivalent of a very high performance full-duplex serial link. The debug >> > capability operation model and registers interface are defined in 7.6.8 >> > of the xHCI specification, revision 1.1. >> > >> > The DbC debug device shares a root port with the xHCI host. By default, >> > the debug capability is disabled and the root port is assigned to xHCI. >> > When the DbC is enabled, the root port will be assigned to the DbC debug >> > device, and the xHCI sees nothing on this port. This implementation uses >> > a sysfs node named <dbc> under the xHCI device to manage the enabling >> > and disabling of the debug capability. >> > >> > When the debug capability is enabled, it will present a debug device >> > through the debug port. This debug device is fully compliant with the >> > USB3 framework, and it can be enumerated by a debug host on the other >> > end of the USB link. As soon as the debug device is configured, a TTY >> > serial device named /dev/ttyDBC0 will be created. >> > >> > One use of this link is running a login service on the debug target. >> > Hence it can be remote accessed by a debug host. Another use case can >> > probably be found in servers. It provides a peer-to-peer USB link >> > between two host-only machines. This provides a reasonable out-of-band >> > communication method between two servers. >> > >> > Signed-off-by: Lu Baolu <baolu...@linux.intel.com> >> > --- >> > .../ABI/testing/sysfs-bus-pci-drivers-xhci_hcd | 25 + >> > drivers/usb/host/Kconfig | 9 + >> > drivers/usb/host/Makefile | 5 + >> > drivers/usb/host/xhci-dbgcap.c | 1016 >> > ++++++++++++++++++++ >> > drivers/usb/host/xhci-dbgcap.h | 247 +++++ >> > drivers/usb/host/xhci-dbgtty.c | 586 +++++++++++ >> > drivers/usb/host/xhci-trace.h | 60 ++ >> > drivers/usb/host/xhci.c | 10 + >> > drivers/usb/host/xhci.h | 1 + >> > 9 files changed, 1959 insertions(+) >> > create mode 100644 >> > Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd >> > create mode 100644 drivers/usb/host/xhci-dbgcap.c >> > create mode 100644 drivers/usb/host/xhci-dbgcap.h >> > create mode 100644 drivers/usb/host/xhci-dbgtty.c >> > >> >> [snip] >> >> > +#define DBC_VENDOR_ID 0x1d6b /* Linux Foundation >> > 0x1d6b */ >> > +#define DBC_PRODUCT_ID 0x0004 /* device 0004 */ >> > >> >> The DbC (xHCI DeBug Capability) is an optional functionality in >> some xHCI host controllers. It will present a super-speed debug >> device through the debug port after it is enabled. >> >> The DbC register set defines an interface for system software >> to specify the vendor id and product id of the debug device. >> These two values will be presented by the debug device in its >> device descriptor idVendor and idProduct fields. >> >> Microsoft Windows have a well established protocol for >> debugging over DbC. And it assigns below values for its use. >> >> USB\VID_045E&PID_062D.DeviceDesc="Microsoft USB Debug Target" >> >> I'm going to use 0x1d6b/0x0004 value pair for DbC use in >> Linux. Do you approve me to do so? > > No. Why can't you use the same ids as Windows? This is implementing > the same protocol, right?
the protocol running on top is 100% vendor specific. More than likely, we would just run kgdb on top of this, right? We really don't support microsoft's debug architecture. -- balbi
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