From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <3e1162e605092207172e74e9cb@mail.gmail.com> Date: Thu, 22 Sep 2005 07:17:37 -0700 From: David Leimbach To: Fans of the OS Plan 9 from Bell Labs <9fans@cse.psu.edu> Subject: Re: [9fans] ndis-ulator for plan 9 In-Reply-To: <836acde3b92a3051ec317b5281c1d047@terzarima.net> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline References: <836acde3b92a3051ec317b5281c1d047@terzarima.net> Topicbox-Message-UUID: 8eeddb9c-ead0-11e9-9d60-3106f5b1d025 On 9/22/05, Charles Forsyth wrote: > > EHCI is an extension to UHCI to enable a much greater degree of bufferi= ng > > it's an incompatible extension since asynchronous requests are no longer = put in the > frame list but go on a separate queue elsewhere, and the descriptors are = different; > it retains many of the annoying features though! > there are extra descriptors to handle the micro-frame intervals > that give the extra speed, and split transactions with the hubs. > the bizarre thing is that the EHCI controller handles only the high-speed > devices, not low-speed or full-speed ones (note that `full speed' is not = `high speed'). > you need a `companion controller' for the low-/full-speed devices, and th= at > controller can be either OHCI or UHCI. of course, that requires special = hardware > to route devices to one controller or another per root port, and new soft= ware > to manage the distribution of work between them. of course, the impleme= nation > can choose from two possible routing schemes. there is an (optional) `li= ght' > reset (distinguished from the usual `soft' reset). such fun! > > All of this begins to remind me why I normally don't muck around in OS kernels. It's so really not fun or interesting to deal with the braindead-ness of hardware. There are people that get off on this stuff but it's not me. I'd rather drink my brains out.