Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754943AbcKJJgX (ORCPT ); Thu, 10 Nov 2016 04:36:23 -0500 Received: from mail-qk0-f193.google.com ([209.85.220.193]:33266 "EHLO mail-qk0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754868AbcKJJdk (ORCPT ); Thu, 10 Nov 2016 04:33:40 -0500 MIME-Version: 1.0 In-Reply-To: References: <20161031162617.10565-1-kyle.roeschley@ni.com> From: Nathan Rossi Date: Thu, 10 Nov 2016 19:33:38 +1000 Message-ID: Subject: Re: [PATCH] ARM: zynq: Reserve correct amount of non-DMA RAM To: Michal Simek Cc: Kyle Roeschley , linux-arm , linux@armlinux.org.uk, Soren Brinkmann , LKML Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2200 Lines: 64 On 10 November 2016 at 18:41, Michal Simek wrote: > + Nathan > > 2016-10-31 17:26 GMT+01:00 Kyle Roeschley : >> >> On Zynq, we haven't been reserving the correct amount of DMA-incapable >> RAM to keep DMA away from it (per the Zynq TRM Section 4.1, it should be >> the first 512k). In older kernels, this was masked by the >> memblock_reserve call in arm_memblock_init(). Now, reserve the correct >> amount excplicitly rather than relying on swapper_pg_dir, which is an >> address and not a size anyway. >> >> Fixes: 46f5b96 ("ARM: zynq: Reserve not DMAable space in front of the >> kernel") >> >> Signed-off-by: Kyle Roeschley Tested-by: Nathan Rossi For reference this causes problems with DEBUG_RODATA (which changed to default yes for CPU_V7 in v4.6) due to padding memory between .head.text and .text, allowing memory below 0x80000 to be available for allocation as non-reserved memory. Regards, Nathan >> --- >> Found when migrating from 4.1 to 4.6. >> >> arch/arm/mach-zynq/common.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/arch/arm/mach-zynq/common.c b/arch/arm/mach-zynq/common.c >> index 6cefdb8..75885bc 100644 >> --- a/arch/arm/mach-zynq/common.c >> +++ b/arch/arm/mach-zynq/common.c >> @@ -59,7 +59,7 @@ void __iomem *zynq_scu_base; >> static void __init zynq_memory_init(void) >> { >> if (!__pa(PAGE_OFFSET)) >> - memblock_reserve(__pa(PAGE_OFFSET), __pa(swapper_pg_dir)); >> + memblock_reserve(__pa(PAGE_OFFSET), 0x80000); >> } >> >> static struct platform_device zynq_cpuidle_device = { >> -- >> 2.9.3 >> >> >> _______________________________________________ >> linux-arm-kernel mailing list >> linux-arm-kernel@lists.infradead.org >> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel > > > > > -- > Michal Simek, Ing. (M.Eng), OpenPGP -> KeyID: FE3D1F91 > w: www.monstr.eu p: +42-0-721842854 > Maintainer of Linux kernel - Microblaze cpu - http://www.monstr.eu/fdt/ > Maintainer of Linux kernel - Xilinx Zynq ARM architecture > Microblaze U-BOOT custodian and responsible for u-boot arm zynq platform