Date: Thu, 09 Dec 2004 13:54:27 -0800 From: Julian Elischer <julian@elischer.org> To: "Kamal R. Prasad" <kamalp@acm.org> Cc: freebsd-hackers@freebsd.org Subject: Re: mmap() Message-ID: <41B8C993.4070807@elischer.org> In-Reply-To: <41B8770C.40707@acm.org> References: <41B20B19.3090204@acm.org> <20041206025126.GO19624@funkthat.com> <41B3F24B.1000903@acm.org> <20041206074237.GP19624@funkthat.com> <41B5DF9B.50501@acm.org> <20041207221919.GQ19624@funkthat.com> <20041207222115.GA74736@freebie.xs4all.nl> <41B68DF5.6070708@acm.org> <20041208090504.GT19624@funkthat.com> <41B8770C.40707@acm.org>
next in thread | previous in thread | raw e-mail | index | archive | help
Kamal R. Prasad wrote: > > My usb device probably doesn't have a dma controller, so I don't think > the bulk pipe can use any memory allocated by bus_dma. [Pl. correct me > if Im wrong this]. > thanks > -kamal > all USB devices use full scatter-gather DMA. UHCI and OHCI are limitted I believe to 4GB of ram. EHCI (USB2) has a 64 bit extension that allows all DMAs of data to be 64 bit addresses. I don't know however which chips support the 64 bit extensions.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?41B8C993.4070807>