Date: Sun, 08 Feb 2009 16:09:35 -0800 From: Marcel Moolenaar <xcllnt@mac.com> To: "M. Warner Losh" <imp@bsdimp.com> Cc: svn-src-head@FreeBSD.org, svn-src-all@FreeBSD.org, src-committers@FreeBSD.org Subject: Re: svn commit: r188350 - in head/sys: amd64/amd64 arm/arm dev/usb2/core i386/i386 ia64/ia64 sys Message-ID: <34EFBA0C-FB99-42DB-BF5C-A889348AD393@mac.com> In-Reply-To: <20090208.170515.1031215309.imp@bsdimp.com> References: <200902082254.n18MsxVt037307@svn.freebsd.org> <9E40268E-A2E2-4CAA-AAFE-EB2491175CEE@mac.com> <20090208.170515.1031215309.imp@bsdimp.com>
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On Feb 8, 2009, at 4:05 PM, M. Warner Losh wrote: > In message: <9E40268E-A2E2-4CAA-AAFE-EB2491175CEE@mac.com> > Marcel Moolenaar <xcllnt@mac.com> writes: > : > : On Feb 8, 2009, at 2:54 PM, Warner Losh wrote: > : > : > Author: imp > : > Date: Sun Feb 8 22:54:58 2009 > : > New Revision: 188350 > : > URL: http://svn.freebsd.org/changeset/base/188350 > : > > : > Log: > : > When bouncing pages, allow a new option to preserve the intra- > page > : > offset. This is needed for the ehci hardware buffer rings that > : > assume > : > this behavior. > : > : I thought we ended up with always doing that? > : > : Bounce buffers may or may not be used, so if the page offset > : must be zero for bounce buffers, they must be zero for the > : original DMA request. I see no value in re-aligning the DMA > : request to a page boundary when bounce buffers are used, but > : it is required in some cases to not realign. Hence, why not > : always (and unconditionally) preserve the alignment? > > I'm not entirely sure either. However, at this stage of the game I'd > rather be a little conservative in what we change and do a more > careful and thorough analysis. Fair enough. -- Marcel Moolenaar xcllnt@mac.com
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