svn commit: r232403 - in head/sys: dev/acpica dev/cardbus dev/pci powerpc/ofw sparc64/pci

[Marius Strobl]

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