From: Gerd Knorr <kraxel@bytesex.org>
To: Stephan von Krawczynski <skraw@ithnet.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Memory problem with bttv driver
Date: Wed, 16 Jan 2002 10:57:47 +0100 [thread overview]
Message-ID: <20020116105747.B1190@bytesex.org> (raw)
In-Reply-To: <20020114210039.180c0438.skraw@ithnet.com> <E16QETz-0002yD-00@the-village.bc.nu> <20020115004205.A12407@werewolf.able.es> <slrna480cv.68d.kraxel@bytesex.org> <20020115121424.10bb89b2.skraw@ithnet.com> <20020115142017.D8191@bytesex.org> <20020115161653.A9550@bytesex.org> <20020115173551.5a3fc051.skraw@ithnet.com>
In-Reply-To: <20020115173551.5a3fc051.skraw@ithnet.com>
> > > > Yes. Instead of remapping vmalloced kernel memory it gives you shared
> > > > anonymous pages, then does zerocopy DMA using kiobufs. You may run in
> > > > trouble with >4GB machines.
> > >
> > > Interesting.
> > > What's the problem on > 4GB ?
> >
> > The bt878/848 is a 32bit PCI device, it simply can't go DMA to main
> > memory above 4GB. At least on ia32, on architecures with a iommu
> > (sparc, ...) it should work without trouble.
>
> Sorry, maybe I should have clarified: what is the problem with allocating those
> pages below 4GB in a >4GB box?
do_anonymous_page() may give you pages above 4GB. Need to write my own
nopage handler to fix this.
Gerd
--
#define ENOCLUE 125 /* userland programmer induced race condition */
next prev parent reply other threads:[~2002-01-16 11:55 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-01-14 17:12 Memory problem with bttv driver Stephan von Krawczynski
2002-01-14 17:40 ` Alan Cox
2002-01-14 17:43 ` Stephan von Krawczynski
2002-01-14 17:56 ` Alan Cox
2002-01-14 18:38 ` Stephan von Krawczynski
2002-01-14 19:48 ` Stephan von Krawczynski
2002-01-14 20:03 ` Alan Cox
2002-01-14 20:00 ` Stephan von Krawczynski
2002-01-14 21:17 ` Alan Cox
2002-01-14 23:42 ` J.A. Magallon
2002-01-15 10:17 ` Gerd Knorr
2002-01-15 11:14 ` Stephan von Krawczynski
2002-01-15 13:20 ` Gerd Knorr
2002-01-15 13:46 ` Stephan von Krawczynski
2002-01-15 15:16 ` Gerd Knorr
2002-01-15 16:35 ` Stephan von Krawczynski
2002-01-16 9:57 ` Gerd Knorr [this message]
2002-01-16 17:24 ` Stephan von Krawczynski
[not found] <Pine.LNX.4.21.0201142245040.2118-100000@localhost.localdomain>
2002-01-15 1:55 ` Stephan von Krawczynski
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