From mboxrd@z Thu Jan  1 00:00:00 1970
From: linux@arm.linux.org.uk (Russell King - ARM Linux)
Date: Mon, 8 Oct 2012 18:01:24 +0100
Subject: Problem with 64-bit registers on i.MX53
In-Reply-To: <20121008160841.GM19651@pengutronix.de>
References: <20121008160841.GM19651@pengutronix.de>
Message-ID: <20121008170124.GZ4625@n2100.arm.linux.org.uk>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Mon, Oct 08, 2012 at 06:08:41PM +0200, Michael Olbrich wrote:
> 
> Hi,
> 
> I have a problem that looks like that 64-bit registers (I think) are not
> saved/restored correctly on a context switch. I've reduced it to the
> following test case:
> 
> - Latest Linux mainline kernel (v3.6-8559-ge9eca4d)
>   v3.5 is also affected
> - imx_v6_v7_defconfig
> - arch/arm/boot/dts/imx53-evk.dts
> 
> The following test program is compiled with "-mcpu=cortex-a8 -mfpu=neon
> -O2".
> ------------------------>8--------------------------------
> #include <inttypes.h>
> #include <assert.h>
> 
> volatile int x = 2;
> volatile int64_t y = 2;
> 
> int main() {
> 	volatile int a = 0;
> 	volatile int64_t b = 0;
> 	while (1) {
> 		a = (a + x) % (1 << 30);
> 		b = (b + y) % (1 << 30);
> 		assert(a == b);
> 	}
> }
> ------------------------>8--------------------------------
> The ".. (b + y) .." should result in "vadd.i64 d19, d18, d16" or
> something like that.

Hmm.

Can you send me the output of 'grep ^Features /proc/cpuinfo' please?

Thanks.