Date: Mon, 26 Sep 2005 15:25:05 -0400 From: John Baldwin <jhb@FreeBSD.org> To: freebsd-hackers@freebsd.org, hselasky@c2i.net Subject: Re: bus-dma question Message-ID: <200509261525.06653.jhb@FreeBSD.org> In-Reply-To: <200509261931.46052.hselasky@c2i.net> References: <200509261931.46052.hselasky@c2i.net>
next in thread | previous in thread | raw e-mail | index | archive | help
On Monday 26 September 2005 01:31 pm, Hans Petter Selasky wrote: > Hi, > > I see something suspicious on Amd64, when allocating small blocks of > DMA-able memory: > > bus_dmamap_load_callback: 0x0000000000caf200 > ^^^^ this is physical address > > QH(0xffffff0000caf200) at 0x00caf200: > ^^^^ this is kernel address > > Shouldn't kernel addresses always be different from physical addresses ? No. Especially not on archs like alpha, ia64, amd64, and sparc64 where part of KVA is direct-mapped to physical memory either in hardware (alpha's K0Seg) or via software (ia64, amd64, and sparc64). > When allocating larger blocks of memory I get, for example: > > bus_dmamap_load_callback: 0x000000003bc50000 > > which seems correct. > > --HPS > _______________________________________________ > freebsd-hackers@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-hackers > To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@freebsd.org" -- John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.org
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200509261525.06653.jhb>