linux-kernel - Re: CPU Initiated DMA

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Message-ID: <8739p0u1ov.fsf@inspiron.ap.columbia.edu>
Date:	Mon, 10 Jan 2011 12:08:00 -0500
From:	Nikolaus Rath <Nikolaus@...h.org>
To:	linux-kernel@...r.kernel.org
Subject: Re: CPU Initiated DMA

Ming Lei <tom.leiming@...il.com> writes:
> 2011/1/8 Nikolaus Rath <Nikolaus@...h.org>:
> Hi,
>
>> Hello,
>>
>> I want to write a driver for a rather dumb PCI card, which cannot become
>> bus master itself. Is it possible to use a DMA controller on the
>> mainboard to still transfer data to the card without occupying the CPU?
>>
>> (I believe this is the way DMA used to work on ISA cards, but do recent
>> x86 systems still have a DMA controller for the CPU?)
>>
>> Any pointers are greatly appreciated. I looked into "Linux Device
>> Drivers", but the DMA chapter seems to be only about the device becoming
>> busmaster.
>
> Generally speaking, you can do it certainly if there is dma controller on
> your system.

That sounds promising, thanks. How do I find out if my system has a DMA
controller? (I don't need general C code, I just want to check if I'll
be able to test the driver on my system).


Thanks,

   -Nikolaus

-- 
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