From mboxrd@z Thu Jan 1 00:00:00 1970 From: "H. Peter Anvin" Subject: Re: [PATCH 31/31] memblock: Add memblock_find_in_range() Date: Tue, 27 Jul 2010 23:38:03 -0700 Message-ID: <4C4FD04B.5090503@zytor.com> References: <1279822864-17154-1-git-send-email-yinghai@kernel.org> <1279822864-17154-32-git-send-email-yinghai@kernel.org> <1280295415.1970.245.camel@pasglop> <4C4FC95F.6040806@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Received: from terminus.zytor.com ([198.137.202.10]:46172 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752579Ab0G1Giw (ORCPT ); Wed, 28 Jul 2010 02:38:52 -0400 In-Reply-To: <4C4FC95F.6040806@kernel.org> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Yinghai Lu Cc: Benjamin Herrenschmidt , Ingo Molnar , Thomas Gleixner , Andrew Morton , David Miller , Linus Torvalds , Johannes Weiner , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org On 07/27/2010 11:08 PM, Yinghai Lu wrote: > > for example: > high/low allocation, from first kernel to kexec second kernel, always work fine except system with Qlogic card. > because Qlogic card is using main RAM as EFT etc for card's FW log trace. second kernel have not idea that those RAM > is used by first kernel for that purpose. that the CARD still use that between two kernels. > second kernel could have crash it try to use those ram. > Uhm, no. That's a bug in the Qlogic driver not shutting the card down cleanly. Hacking around that in memory allocation order is braindamaged in the extreme. kexec *cannot* be safe in any way if we don't shut down pending DMA, and what you describe above is DMA. > low/high allocation seems to be safe, second kernel can slip to boot fine. Low to high is just broken. Low memory is a special, desirable resource, and we should minimize the use of it. -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.