Date: Fri, 2 Mar 2012 22:45:52 +0100 From: Marius Strobl <marius@alchemy.franken.de> To: John Baldwin <jhb@freebsd.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r232403 - in head/sys: dev/acpica dev/cardbus dev/pci powerpc/ofw sparc64/pci Message-ID: <20120302214551.GB1635@alchemy.franken.de> In-Reply-To: <201203022038.q22Kc5vd046376@svn.freebsd.org> References: <201203022038.q22Kc5vd046376@svn.freebsd.org>
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On Fri, Mar 02, 2012 at 08:38:05PM +0000, John Baldwin wrote: > Author: jhb > Date: Fri Mar 2 20:38:04 2012 > New Revision: 232403 > URL: http://svn.freebsd.org/changeset/base/232403 > > Log: > - Add a bus_dma tag to each PCI bus that is a child of a Host-PCI bridge. > The tag enforces a single restriction that all DMA transactions must not > cross a 4GB boundary. Note that while this restriction technically only > applies to PCI-express, this change applies it to all PCI devices as it > is simpler to implement that way and errs on the side of caution. Hrm, wouldn't it have been more appropriate to implement this in the Host-PCI bridges instead? Probably for anything but x86 this would allow to easily distinguish at least between PCI and PCI-Express capable bus hierarchies and would move the PAE workaround to the MD bits to where it belongs. Marius
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