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Date:      Mon, 22 Jan 2001 13:19:43 -0800
From:      Alfred Perlstein <bright@wintelcom.net>
To:        Warner Losh <imp@harmony.village.org>
Cc:        Robert Lipe <robertlipe@usa.net>, freebsd-hackers@FreeBSD.ORG
Subject:   Re: contigmalloc, M_WAITOK, & leaks.
Message-ID:  <20010122131943.E26076@fw.wintelcom.net>
In-Reply-To: <200101222108.f0ML8X912362@harmony.village.org>; from imp@harmony.village.org on Mon, Jan 22, 2001 at 02:08:33PM -0700
References:  <20010122125444.C26076@fw.wintelcom.net> <20010122110642.B10504@rjlhome.sco.com> <20010122100524.D7240@fw.wintelcom.net> <20010122124539.F10504@rjlhome.sco.com> <20010122105227.E7240@fw.wintelcom.net> <20010122132647.I10504@rjlhome.sco.com> <20010122121033.A26076@fw.wintelcom.net> <20010122145550.O10504@rjlhome.sco.com> <20010122125444.C26076@fw.wintelcom.net> <200101222108.f0ML8X912362@harmony.village.org>

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* Warner Losh <imp@harmony.village.org> [010122 13:09] wrote:
> In message <20010122125444.C26076@fw.wintelcom.net> Alfred Perlstein writes:
> : > Yes, this looks to be much closer to the interface I really wanted
> : > anyway.  I see no man pages for them.  Is there any doc anywhere?  "Read
> : > the source and look at existing examples" will do if it must but any
> : > pointers to better doc are appreciated.
> : 
> : I know of no docs, I don't write drivers. (lucky me)
> 
> There are no docs.  You can find docs on NetBSD's busdma
> implementation from all the usual places.  The busdma interface for
> FreeBSD is close to NetBSD's, but the implementation is somewhat
> different.  FreeBSD's busspace, however, is missing many parts of the
> NetBSD interface, and implementing those would be hard give newbus.
> At leas that was my take when I tried.

It would be uber-nice to have docs, the interface has only existed
for afaik 2-3 years now. :(

> 
> : I don't know, Bill Paul explained that the normal busdma stuff is
> : pretty broken for chunks too small.  Basically, disks work, network
> : cards won't because mbufs are too small.
> 
> Yuck.  We should fix that.

I don't know about "fixing it", netbsd seems to offer a different
interface for it (bus_dmamap_load_mbuf).  Possibly for effeciency
reasons but i'm not sure.

-- 
-Alfred Perlstein - [bright@wintelcom.net|alfred@freebsd.org]
"I have the heart of a child; I keep it in a jar on my desk."


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