Date: Sat, 05 Jun 2010 20:33:48 -0600 (MDT) From: "M. Warner Losh" <imp@bsdimp.com> To: xcllnt@mac.com Cc: svn-src-projects@FreeBSD.org, src-committers@FreeBSD.org, nwhitehorn@FreeBSD.org Subject: Re: svn commit: r208850 - projects/ppc64/sys/powerpc/include Message-ID: <20100605.203348.651115405925906974.imp@bsdimp.com> In-Reply-To: <184A275D-B98A-4DBF-9F4D-22F27B9319DD@mac.com> References: <201006052041.o55KfMF6032155@svn.freebsd.org> <184A275D-B98A-4DBF-9F4D-22F27B9319DD@mac.com>
next in thread | previous in thread | raw e-mail | index | archive | help
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...
Warner
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20100605.203348.651115405925906974.imp>