From: Rik van Riel <riel@conectiva.com.br> To: Matt Dillon <dillon@earth.backplane.com> Cc: Sergey Babkin <babkin@bellatlantic.net>, David Greenman <dg@root.com>, <hackers@freebsd.org>, <murray@freebsd.org>, <jkh@freebsd.org> Subject: Re: Recommendation for minor KVM adjustments for the release Message-ID: <Pine.LNX.4.33L.0108191747080.5646-100000@imladris.rielhome.conectiva> In-Reply-To: <200108191907.f7JJ7cM45828@earth.backplane.com>
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On Sun, 19 Aug 2001, Matt Dillon wrote: > In FreeBSD land the use-case would simply be our physical-backed-shared- > memory feature. We could implement the 8-byte MMU extensions in the > PMAP code as a kernrel option to be able to access ram > 4GB without > having to change anything else in the kernel (not even vm_page_t or > the pmap supporting structures) *IF* we only use the ram > 4GB in > physical-backed SysV shared memory mappings. Actually, using it for normal process anonymous memory and file cache is pretty easy. If FreeBSD still has the 16MB ISA bounce buffer code working, there is little reason why the same kind of bounce buffer setup couldn't be done for 32-bit PCI DMA. In Linux this is hidden in the block IO layer, neither the VM or the disk device drivers have to know about it. regards, Rik -- IA64: a worthy successor to i860. http://www.surriel.com/ http://distro.conectiva.com/ Send all your spam to aardvark@nl.linux.org (spam digging piggy) To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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