NetBSD Problem Report #59288

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Date: Sun, 13 Apr 2025 13:03:47 +0000 (UTC)
From: campbell+netbsd@mumble.net
Reply-To: campbell+netbsd@mumble.net
To: gnats-bugs@NetBSD.org
Subject: uhid(4): story of report byte id is unclear
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>Number:         59288
>Category:       kern
>Synopsis:       uhid(4): story of report byte id is unclear
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          doc-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Apr 13 13:05:00 +0000 2025
>Originator:     Taylor R Campbell
>Release:        current, 10, 9, ...
>Organization:
The NetUHID Documentation
>Environment:
>Description:
In some circumstances, the packets read and written on /dev/uhidN, either with read(2)/write(2) or with ioctl(USB_GET_REPORT)/ioctl(USB_SET_REPORT0, possibly limited to raw mode or not-raw mode, have a report id byte prefixed, but in other circumstances, they do not.

This was very confusing to me when I last dealt with /dev/uhidN.  But evidently the tricky issue is not written down anywhere obvious like the uhid(4) man page or comments in sys/dev/usb/uhid.c.  So now I have to figure it out afresh from the code and/or spec and/or doing science on a physical device.

Also the link http://www.usb.org/developers/devclass_docs/HID1_11.pdf in uhid.c to the USB HID spec is broken.
>How-To-Repeat:
attempt to write or port code involving /dev/uhidN
>Fix:
Yes, please!

Also make sure to include an archive.org link for the spec so it doesn't break again.

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