From: Arnd Bergmann <arnd@arndb.de>
To: linux-arm-kernel@lists.infradead.org
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>,
        Russell King - ARM Linux <linux@arm.linux.org.uk>,
        "thomas.petazzoni@free-electrons.com" 
	<thomas.petazzoni@free-electrons.com>,
        "mathieu.poirier@linaro.org" <mathieu.poirier@linaro.org>,
        "stefano.stabellini@eu.citrix.com" <stefano.stabellini@eu.citrix.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Liviu Dudau <Liviu.Dudau@arm.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "ezequiel.garcia@free-electrons.com" 
	<ezequiel.garcia@free-electrons.com>
Subject: Re: [PATCH] ARM: supplementing IO accessors with 64 bit capability
Date: Fri, 24 Oct 2014 12:37:33 +0200
Message-ID: <7410166.17BME9oUT7@wuerfel>
User-Agent: KMail/4.11.5 (Linux/3.16.0-10-generic; KDE/4.11.5; x86_64; ; )
In-Reply-To: <alpine.LFD.2.11.1410231607340.6969@knanqh.ubzr>
References: <1413993983-17310-1-git-send-email-mathieu.poirier@linaro.org> <20141023195119.GL27405@n2100.arm.linux.org.uk> <alpine.LFD.2.11.1410231607340.6969@knanqh.ubzr>
MIME-Version: 1.0
Content-Transfer-Encoding: 7Bit
Content-Type: text/plain; charset="us-ascii"
Sender: linux-kernel-owner@vger.kernel.org

On Thursday 23 October 2014 16:15:19 Nicolas Pitre wrote:
> On Thu, 23 Oct 2014, Russell King - ARM Linux wrote:
> 
> > On Thu, Oct 23, 2014 at 03:47:32PM -0400, Nicolas Pitre wrote:
> > > On Wed, 22 Oct 2014, Catalin Marinas wrote:
> > > 
> > > > On Wed, Oct 22, 2014 at 05:06:23PM +0100, mathieu.poirier@linaro.org wrote:
> > > > > +#if __LINUX_ARM_ARCH__ >= 5
> > > > 
> > > > My old ARMv5 book does not list LDRD/STRD. It looks like they only come
> > > > with ARMv5TE. Are there any processors prior to this supported by the
> > > > kernel?
> > > 
> > > We still supports ARMv4 targets.
> > > 
> > > As far as I know, all the ARMv5 targets we support are also TE capable.
> > 
> > Not quite.  We have ARM1020, which according to our proc-*.S files is
> > only ARMv5T, not ARMv5TE.

Does this actually work when we are building with -march=armv5te?

The Makefile contains this line:

arch-$(CONFIG_CPU_32v5) =-D__LINUX_ARM_ARCH__=5 $(call cc-option,-march=armv5te,-march=armv4t)

which looks like it would break for ARM1020.


On a related note, I also wonder about this part:

tune-$(CONFIG_CPU_ARM946E)      =$(call cc-option,-mtune=arm9e,-mtune=arm9tdmi)
tune-$(CONFIG_CPU_ARM920T)      =-mtune=arm9tdmi
tune-$(CONFIG_CPU_ARM922T)      =-mtune=arm9tdmi
tune-$(CONFIG_CPU_ARM925T)      =-mtune=arm9tdmi
tune-$(CONFIG_CPU_ARM926T)      =-mtune=arm9tdmi

I stumbled over this a while ago and couldn't figure it out. Does ARM926T
actually exist, or is that a mistake that should actually be ARM926E?

If this is always ARM926E, shouldn't we build with -mtune=arm9e as we do
for ARM946E?

> Oh well.  Never saw such a beast in the field though.

The only ARM10 implementation aside from integrator/realview that I'm aware
of is an ARM1026E based Conexant/Ikanos DSL modem SoC (CX94xxx), and that
is of course ARMv5TE.

> Maybe to be on the very safe side, given that no ARMV5TE is likely to 
> need 64-bit IO accessors at this point, this could simply be 
> __LINUX_ARM_ARCH__ >= 6 instead.

Which drivers need that support anyway? We definitely need to ensure
that we don't try to build them on architectures without this support
when CONFIG_COMPILE_TEST is set.

	Arnd
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/