Date: Tue, 31 Aug 2010 15:39:56 -0400 From: John Baldwin <jhb@freebsd.org> To: Matthew Jacob <mj@feral.com> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org, Pyun YongHyeon <yongari@freebsd.org> Subject: Re: svn commit: r212061 - head/sys/dev/bge Message-ID: <201008311539.57185.jhb@freebsd.org> In-Reply-To: <4C7D41E9.7060907@feral.com> References: <201008311733.o7VHXmxX037013@svn.freebsd.org> <201008311350.17175.jhb@freebsd.org> <4C7D41E9.7060907@feral.com>
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On Tuesday, August 31, 2010 1:54:49 pm Matthew Jacob wrote: > But not amd64 please. > > > Keep in mind the PAE case where you cannot effectively specify a 4GB > > boundary. I used a 2GB boundary for twa(4) in the PAE case to deal > > with the boundary issue. Probably though, bus_dma should just always > > enforce a 4GB boundary, at least on x86. Yes, thinking about this more, only i386 + PAE is special. All other cases could represent the 4GB boundary restriction in a bus dma tag for the PCI bus (or in the platform-specific Host-PCI bridge drivers). For i386 + PAE it might make sense to always enforce a 4GB boundary in the bus_dma code itself. -- John Baldwin
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