From mboxrd@z Thu Jan 1 00:00:00 1970 From: Taniya Das Subject: Re: arm_memblock_steal() API usage Date: Wed, 04 Apr 2012 10:36:05 +0530 Message-ID: <4F7BD6BD.7040102@codeaurora.org> References: <4F7A76B3.3070405@codeaurora.org> <20120403073053.GO24211@n2100.arm.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from wolverine01.qualcomm.com ([199.106.114.254]:50838 "EHLO wolverine01.qualcomm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750908Ab2DDFG2 (ORCPT ); Wed, 4 Apr 2012 01:06:28 -0400 In-Reply-To: <20120403073053.GO24211@n2100.arm.linux.org.uk> Sender: linux-arm-msm-owner@vger.kernel.org List-Id: linux-arm-msm@vger.kernel.org To: Russell King - ARM Linux Cc: linux-arm-kernel@lists.infradead.org, linux-arm-msm@vger.kernel.org, tsoni@codeaurora.org RMK, On 03-Apr-12 1:00 PM, Russell King - ARM Linux wrote: > On Tue, Apr 03, 2012 at 09:34:03AM +0530, Taniya Das wrote: >> I have a requirement where I need around ~100 bytes of memory to save >> contents of >> registers to a non-cached area before going into low power mode. >> >> I did do some analysis on a 1GB RAM device of allocating 8 bytes using >> the API and the below was the result >> was showing allocating only 8 bytes. >> >> API used : - arm_memblock_steal(SZ_8, SZ_64K);--> physical address >> returned is 0x3b1f0000 > It's silly to use this for the above purpose. Why not just use kmalloc > and cache flushing to ensure that the data is pushed out to RAM? We don't want to do a kmalloc and flush, we want to do something similar to how OMAP4 does, keeping aside a chunk of RAM for saving the contents. But my only concern what will be the minimum amount of memory allocated by arm_memblock_steal? >> Also is this API advisable for devices with low system RAM? > No. -- Thanks& Regards, Taniya Das. Sent by an employee of the Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.