From: jonathan.austin@arm•com (Jonathan Austin)
To: linux-arm-kernel@lists•infradead.org
Subject: Building for MMU-less vexpress targets
Date: Tue, 08 Jan 2013 19:01:19 +0000 [thread overview]
Message-ID: <50EC6CFF.5070309@arm.com> (raw)
In-Reply-To: <alpine.LFD.2.02.1211061802240.21033@xanadu.home>
Nicolas,
On 06/11/12 23:14, Nicolas Pitre wrote:
> On Tue, 6 Nov 2012, Arnd Bergmann wrote:
>
>> On Tuesday 06 November 2012, Nicolas Pitre wrote:
>
>> The two options are either to make
>> vexpress be single-platform when building for !MMU, or to allow multiplatform
>> kernels to be built without MMU support in principle. I think the second
>> option is more logical and avoids complex Kconfig constructs.
>
> Well, I'd rather prefer to think that the first option is the most
> logical between those 2 options, regardless of Kconfig complexity
> issues.
>
> I didn't look, but just making MULTIPLATFORM depend on !MMU, and
> VEXPRESS depend on MULTIPLATFORM || MMU should be close to what is
> needed, no?
>
I've spent a little bit of time trying this, as both Arnd and you seemed
to be happy with a solution along these lines.
However, I can't seem to make it fall out quite so trivially so I wonder
if you'd mind clarifying what you were expecting:
The problem that I see when I try to do this is that ARCH_VEXPRESS no
longer exists in the 'choice' for "ARM system type" in arch/arm/Kconfig.
A solution that allows selection of VEXPRESS as a single platform (!MMU)
and multi-platform (MMU) appears to need an entry in that 'choice' for
the single platform case, and a config option in
arch/arm/mach-vexpress/Kconfig for the multiplatform one.
So it seems to me we need a shim in one of those two locations...
As Will suggested a while back, the shim in arch/arm/Kconfig could look
like:
---8<---
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 335e220..0561d87 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -305,6 +305,11 @@ config ARCH_REALVIEW
help
This enables support for ARM Ltd RealView boards.
+config ARCH_VEXPRESS_NOMMU
+ bool "ARM Ltd. Versatile Express family (nommu)"
+ depends on !MMU
+ select ARCH_VEXPRESS
+
config ARCH_VERSATILE
bool "ARM Ltd. Versatile family"
select ARCH_WANT_OPTIONAL_GPIOLIB
---->8----
With the other perhaps being to merge the ARCH_VEXPRESS option back in
to the 'choice' and create a ARCH_VEXPRESS_MULTI elsewhere...
Is that the sort of thing you had in mind, or is there another way
around that I'm missing?
Thanks,
Jonny
next prev parent reply other threads:[~2013-01-08 19:01 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-05 17:36 Building for MMU-less vexpress targets Will Deacon
2012-11-05 18:03 ` Pawel Moll
2012-11-05 18:13 ` Will Deacon
2012-11-05 19:08 ` Arnd Bergmann
2012-11-06 12:20 ` Will Deacon
2012-11-06 17:33 ` Arnd Bergmann
2012-11-06 18:34 ` Will Deacon
2012-11-06 20:35 ` Arnd Bergmann
2012-11-06 20:58 ` Nicolas Pitre
2012-11-06 21:14 ` Arnd Bergmann
2012-11-06 22:14 ` Russell King - ARM Linux
2012-11-06 22:59 ` Rob Herring
2012-11-07 12:59 ` Arnd Bergmann
2012-11-07 13:39 ` Russell King - ARM Linux
2012-11-06 23:14 ` Nicolas Pitre
2012-11-07 10:21 ` Will Deacon
2012-11-07 13:29 ` Arnd Bergmann
2013-01-08 19:01 ` Jonathan Austin [this message]
2013-01-08 19:11 ` Arnd Bergmann
2013-01-08 19:22 ` Nicolas Pitre
2012-11-06 22:51 ` Jamie Lokier
2012-11-06 23:40 ` Nicolas Pitre
2012-11-06 23:46 ` Jamie Lokier
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