Date: Sat, 5 Jun 2010 21:38:30 -0600 From: Scott Long <scottl@samsco.org> To: "M. Warner Losh" <imp@bsdimp.com> Cc: svn-src-projects@FreeBSD.org, xcllnt@mac.com, nwhitehorn@FreeBSD.org, src-committers@FreeBSD.org Subject: Re: svn commit: r208850 - projects/ppc64/sys/powerpc/include Message-ID: <516EEDC6-069A-4780-84DF-BBFF43ABCDE5@samsco.org> In-Reply-To: <20100605.203348.651115405925906974.imp@bsdimp.com> References: <201006052041.o55KfMF6032155@svn.freebsd.org> <184A275D-B98A-4DBF-9F4D-22F27B9319DD@mac.com> <20100605.203348.651115405925906974.imp@bsdimp.com>
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On Jun 5, 2010, at 8:33 PM, M. Warner Losh wrote: > In message: <184A275D-B98A-4DBF-9F4D-22F27B9319DD@mac.com> > Marcel Moolenaar <xcllnt@mac.com> writes: > : > : On Jun 5, 2010, at 1:41 PM, Nathan Whitehorn wrote: > : > : > Author: nwhitehorn > : > Date: Sat Jun 5 20:41:22 2010 > : > New Revision: 208850 > : > URL: http://svn.freebsd.org/changeset/base/208850 > : > > : > Log: > : > BUS_SPACE_UNRESTRICTED is a flag, not an address, so it should be an int, > : > not a long. > : > : This probably isn't right. How would you distinguish between a 32-bit > : maximum of and unlimited if both can have the value 0xFFFFFFFF. > : Making BUS_SPACE_UNRESTRICTED a long prevents zero-extension to 64-bit > : and thus prevents this ambiguity. > > But this define is used for busdma's number of segments. It isn't > used for an address at all... > > from the busdma man page for bus_dma_tag_create: > nsegments Number of discontinuities (scatter/gather segments) > allowed in a DMA mapped region. If there is no > restriction, BUS_SPACE_UNRESTRICTED may be speci- > fied. > > so an argument consistent with the definition of nsegments is what is > needed. The man page doesn't specify a type for nsegments, but > sys/bus_dma.h defines it as: > > int bus_dma_tag_create(bus_dma_tag_t parent, bus_size_t alignment, > bus_size_t boundary, bus_addr_t lowaddr, > bus_addr_t highaddr, bus_dma_filter_t *filtfunc, > void *filtfuncarg, bus_size_t maxsize, int nsegments, > bus_size_t maxsegsz, int flags, bus_dma_lock_t *lockfunc, > void *lockfuncarg, bus_dma_tag_t *dmat); > > so it is more proper to have it be an int than a long. > > I got tripped up on this stupid name too when I was adding it for > MIPS. Any why it is in a MD file instead of an MI file is beyond me. > I think it should be defined in sys/bus_dma.h, but maybe I'm just nuts... > No, you're not nuts. I've had a grand unification of MI/MD parts of busdma on my mind for years, and probably at least 2 or 3 aborted attempts lying around in old defunct trees. Any unification is going to risk API/ABI changes, so I ultimately don't want to do it simply for cleanliness sake. Scotthelp
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