Date: Mon, 18 Feb 2019 17:28:26 -0600 From: "Apollo D. Sharpe, Sr." <demetrioussharpe@netscape.net> To: Warner Losh <imp@bsdimp.com> Cc: Hans Petter Selasky <hps@selasky.org>, "freebsd-usb@FreeBSD.org" <freebsd-usb@freebsd.org> Subject: Re: Questions about the USB HID device drivers Message-ID: <2a062140-dc0f-e5e9-e1c9-ba557f963b41@netscape.net> In-Reply-To: <CANCZdfoVjJVBSS2=Uh8Kr=cUqsd=Qw9kLOS8u8k_7nZ3g_jDyw@mail.gmail.com> References: <fd7883c8-604e-e7d7-b135-d1d957938e7c@netscape.net> <9c6a87dd-cf7c-d0eb-82f1-5e904baaf05f@selasky.org> <325834a2-d9f1-a1f4-dff1-7f724aeb4907@netscape.net> <6762c7c9-f9dc-f7d2-0b1f-c2f6e2816cd7@selasky.org> <3724cc29-b682-2395-bd95-cbfa418ad9f2@netscape.net> <0cbc66cd-9007-878e-8bc3-f623364729d4@selasky.org> <d792f27e-5e55-e5ca-eb89-b7a8704200e0@netscape.net> <CANCZdfoVjJVBSS2=Uh8Kr=cUqsd=Qw9kLOS8u8k_7nZ3g_jDyw@mail.gmail.com>
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On 2/18/19 3:18 PM, Warner Losh wrote: > Yes and no. If the unique prefix has / in it, devfs puts it in a subdir. If I'm reading the code right, the unique prefix is basically driver_t::name. Is that correct? If so, I haven't seen a device name (in the entire tree) that has "/" in it's device name. Maybe I'm missing something here. > Way back in the days of yore, it was 100% userland to create the > hierarchy. You did your mknod and that was that. We had big tables of > major numbers that mapped device names to the kernel. > > There were problems with this: not the least was that major numbers > were a limited resource and soon ran out. Now, devfs manages > everything. You can get it to create many different hierarchies. see > devfs(8) for details. > I can imagine how much of a pain that was. Though, it looks as though not too many people bother changing beyond the default devfs.rules and devfs.conf files -they also seem to be a pain to deal with. It's a reasonable solution for servers, however it would be much more valuable on desktops to have /dev/input/* for various input devices. I guess I'm going to have to figure out how to make devices publish themselves in /dev based on their primary function. Thank you, and everyone else, for taking the time to explain the setup to me. -- Regards, Apollo D. Sharpe, Sr.
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