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From: Alessandro Rubini <rubini@gnudd.com>
To: hpa@zytor.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 22:32:20 +0200	[thread overview]
Message-ID: <20120412203220.GA27629@mail.gnudd.com> (raw)
In-Reply-To: <4F87388C.300@zytor.com>

>>   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.

Why not? CONFIG_ISA is a compile-time choice. I thought that if you
compile for non-ISA systems you may reuse the zone mechanism with a
different split.

But if not a compile-time thing, would you accept it at run time?
I feel it's not a beautiful approach, because it must clearly be
masked by #ifndef CONFIG_ISA or such. Worse, you must know the zone
split at the beginning, before you scan the PCI bus and find your
devices.

thanks
/alessandro

  parent reply	other threads:[~2012-04-12 20:32 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
2012-04-12 18:01     ` H. Peter Anvin
2012-04-12 20:15     ` Alessandro Rubini
2012-04-12 20:18       ` H. Peter Anvin
2012-04-12 20:32       ` Alessandro Rubini [this message]
2012-04-12 20:47         ` H. Peter Anvin
2012-04-14 11:38           ` Ingo Molnar
2012-04-11 10:19   ` Alessandro Rubini
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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