Date: Mon, 7 Jul 2014 01:54:24 -0400 (EDT) From: Garrett Wollman <wollman@hergotha.csail.mit.edu> To: adrian@freebsd.org Cc: freebsd-arch@freebsd.org Subject: Re: [patch] axe RF_TIMESHARE? Message-ID: <201407070554.s675sOdQ051033@hergotha.csail.mit.edu> In-Reply-To: <CAJ-Vmong-1_k=TBugK5kvKnp-tUeJ3w5fXTzSXQsyYhD1UUf0w@mail.gmail.com> References: <CAJ-VmokLfZ1kwqCeCmbJmxBgZXCgdc=9BTD1Feyf0_%2BVPiZKmA@mail.gmail.com> <201407070047.s670lWUv022054@gw.catspoiler.org>
next in thread | previous in thread | raw e-mail | index | archive | help
In article <CAJ-Vmong-1_k=TBugK5kvKnp-tUeJ3w5fXTzSXQsyYhD1UUf0w@mail.gmail.com>, adrian@freebsd.org writes: >On 6 July 2014 17:47, Don Lewis <truckman@freebsd.org> wrote: >> On 6 Jul, Adrian Chadd wrote: >>> Hi, >>> >>> What's it supposed to be used for? >> >> My understanding it that it is supposed to be used to allow two more >> devices to claim the same resource, such as an I/O port range, but only >> one device can be active at a time. > >Interesting. I wonder what kinds of things would want to do this. Well, when I included it the original rman implementation, I had a few applications in mind: - shared interrupts on the ISA bus - some weird stuff that people were doing on parallel ports - if you had some device with a really big shared-memory region that you might want to be able to turn on and off to allow other devices to use that address space It's been more than a decade since I wrote that code, and I think pretty much every conceivable use for it has long since been overtaken by events. In any modern situation where you might want to use this, you probably need the cooperation of higher-level code to make it work anyway, so you might as well implement it at that layer instead. So yes, please, do make it go away. Simpler and easier to understand is better. -GAWollman
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201407070554.s675sOdQ051033>