On Wed, Apr 26, 2023 at 12:17:53PM +0200, Konrad Gräfe wrote: > > As the CDC-ECM specification states the host MAC address must be sent to > the host as an uppercase hexadecimal string: > The Unicode character is chosen from the set of values 30h through > 39h and 41h through 46h (0-9 and A-F). > > However, snprintf(.., "%pm", ..) generates a lowercase MAC address > string. While most host drivers are tolerant to this, UsbNcm.sys on > Windows 10 is not. Instead it uses a different MAC address with all > bytes set to zero including and after the first byte containing a > lowercase letter. On Windows 11 Microsoft fixed it, but apparently they > did not backport the fix. > > This change fixes the issue by upper-casing the MAC to comply with the > specification. > > Signed-off-by: Konrad Gräfe <k.graefe@xxxxxxxxxxx> > --- > V1 -> V2: Fixed checkpatch.pl warnings There is no "v2" in the subject line, so our tools will get confused and have no idea this is a newer patch. Please fix up and send a v3? > snprintf(host_addr, len, "%pm", dev->host_mac); Is there no option to print a mac address with all uppercase? If not, why not add that instead as it's needed here and maybe other places, right? thanks, greg k-h
