From: Oliver Neukum <oneukum@suse.de>
To: Casey Dahlin <cdahlin@redhat.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: A question about ZONE_DMA
Date: Wed, 13 Oct 2010 16:57:07 +0200 [thread overview]
Message-ID: <201010131657.07187.oneukum@suse.de> (raw)
In-Reply-To: <20101013145240.GE12467@foucault.redhat.com>
Am Mittwoch, 13. Oktober 2010, 16:52:41 schrieb Casey Dahlin:
> Hi all,
>
> So if I understand correctly, ZONE_DMA exists to separate and preserve the
> chunk of memory to which older ISA cards are capable of doing DMA. The question
> that arises for me is:
>
> 1) Why do /all/ 32-bit boxes have a ZONE_DMA when surely only a tiny and
> shrinking number of them have a need for it?
You don't know before you load the module of the driver that needs it.
> 2) Why do /any/ 64-bit boxes have a ZONE_DMA? Is there really some godless
> monster out there who put an early ISA bridge and a 64-bit CPU on the same
> motherboard?!
Parports can use DMA and are generally ISA.
Regards
Oliver
next prev parent reply other threads:[~2010-10-13 14:57 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-13 14:52 A question about ZONE_DMA Casey Dahlin
2010-10-13 14:57 ` Oliver Neukum [this message]
2010-10-13 14:57 ` Arnd Bergmann
2010-10-13 15:12 ` Casey Dahlin
2010-10-13 16:07 ` Andi Kleen
2010-10-13 20:53 ` David Rientjes
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