usb: add serial number generator

This patch adds a function which creates unique serial numbers for usb
devices and puts it into use.  Windows guests tend to become unhappy if
they find two identical usb devices in the system.  Effects range from
non-functional devices (with yellow exclamation mark in device manager)
to BSODs.  Handing out unique serial numbers to devices fixes this.

With this patch applied almost all emulated devices get a generated,
unique serial number.  There are two exceptions:

 * usb-storage devices will prefer a user-specified serial number
   and will only get a generated number in case the serial property
   is unset.
 * usb-hid devices keep the fixed serial number "42" as it is used
   to signal "remote wakeup actually works".
   See commit 7b074a22dab4bdda9864b933f1bc811a3db42845

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/hw/usb/desc.h b/hw/usb/desc.h
index d164e8f..7cf5442 100644
--- a/hw/usb/desc.h
+++ b/hw/usb/desc.h
@@ -171,6 +171,7 @@ int usb_desc_other(const USBDescOther *desc, uint8_t *dest, size_t len);
 void usb_desc_init(USBDevice *dev);
 void usb_desc_attach(USBDevice *dev);
 void usb_desc_set_string(USBDevice *dev, uint8_t index, const char *str);
+void usb_desc_create_serial(USBDevice *dev);
 const char *usb_desc_get_string(USBDevice *dev, uint8_t index);
 int usb_desc_string(USBDevice *dev, int index, uint8_t *dest, size_t len);
 int usb_desc_get_descriptor(USBDevice *dev, int value, uint8_t *dest, size_t len);