From: "H. Peter Anvin" <hpa@zytor.com>
To: Alessandro Rubini <rubini@gnudd.com>
Cc: mingo@elte.hu, akpm@linux-foundation.org,
jbarnes@virtuousgeek.org, fujita.tomonori@lab.ntt.co.jp,
linux-kernel@vger.kernel.org, tglx@linutronix.de,
mingo@redhat.com, x86@kernel.org, giancarlo.asnaghi@st.com,
alan@linux.intel.com
Subject: Re: [PATCH V4 1/3] x86: introduce CONFIG_X86_DEV_DMA_OPS
Date: Thu, 12 Apr 2012 13:18:20 -0700 [thread overview]
Message-ID: <4F87388C.300@zytor.com> (raw)
In-Reply-To: <20120412201533.GA26533@mail.gnudd.com>
On 04/12/2012 01:15 PM, Alessandro Rubini wrote:
>
> The current approach is using swiotlb and it works pretty well, though
> with a limit of 4MB of swiotlb area. I've been considering use of the
> DMA zone to this aim: internally I have some half-working thing that
> resuses the ISA DMA zone for our own aims, raising the DMA limit to
> 512MB.
>
> Do you think the approach may make sense? I use this basic
> thing in Kconfig, to rely on GFP_DMA for the rest:
>
> config MAX_DMA_PADDR
> int
> default 536870912 if MAX_DMA_PADDR_512M
> default 16777216
>
> config MAX_DMA_PADDR_512M
> bool
>
> (actually, we'd benefit from being able to use hex in defaults)
>
> Is this worth exploring, to possibly submit a patch in this direction?
>
Not as a compile-time patch.
-hpa
next prev parent reply other threads:[~2012-04-12 20:18 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-13 7:28 [PATCH V4 0/3] *** SUBJECT HERE *** Alessandro Rubini
2012-03-13 7:30 ` [PATCH V4 1/3] x86: introduce CONFIG_X86_DEV_DMA_OPS Alessandro Rubini
2012-03-14 6:56 ` Ingo Molnar
2012-04-11 10:19 ` Alessandro Rubini
2012-04-12 18:01 ` H. Peter Anvin
2012-04-12 20:15 ` Alessandro Rubini
2012-04-12 20:18 ` H. Peter Anvin [this message]
2012-04-12 20:32 ` Alessandro Rubini
2012-04-12 20:47 ` H. Peter Anvin
2012-04-14 11:38 ` Ingo Molnar
2012-03-13 7:30 ` [PATCH V4 2/3] x86: introduce CONFIG_X86_DMA_REMAP Alessandro Rubini
2012-03-13 7:30 ` [PATCH V4 3/3] x86/PCI: initial support for sta2x11 I/O hub Alessandro Rubini
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