Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752931AbaFMIBT (ORCPT ); Fri, 13 Jun 2014 04:01:19 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54437 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751278AbaFMIBS (ORCPT ); Fri, 13 Jun 2014 04:01:18 -0400 Date: Fri, 13 Jun 2014 16:00:28 +0800 From: WANG Chao To: Borislav Petkov Cc: Vivek Goyal , Dave Young , mjg59@srcf.ucam.org, bhe@redhat.com, jkosina@suse.cz, greg@kroah.com, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, ebiederm@xmission.com, hpa@zytor.com, akpm@linux-foundation.org Subject: Re: [PATCH 07/13] kexec: Implementation of new syscall kexec_file_load Message-ID: <20140613080028.GK15034@dhcp-17-89.nay.redhat.com> References: <1401800822-27425-1-git-send-email-vgoyal@redhat.com> <1401800822-27425-8-git-send-email-vgoyal@redhat.com> <20140606065605.GE2785@dhcp-17-89.nay.redhat.com> <20140606181859.GK1526@redhat.com> <20140609021122.GB1924@darkstar.nay.redhat.com> <20140609053538.GA2874@dhcp-17-89.nay.redhat.com> <20140609154137.GD22049@redhat.com> <20140613075011.GA4751@pd.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140613075011.GA4751@pd.tnic> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/13/14 at 09:50am, Borislav Petkov wrote: > On Mon, Jun 09, 2014 at 11:41:37AM -0400, Vivek Goyal wrote: > > IIUC, COMMAND_LINE_SIZE gives max limits of running kernel and it does > > not tell us anything about command line size supported by kernel being > > loaded. > > Whatever you do, you do need a sane default because even querying the > boot protocol is not reliable as the to-be-loaded kernel's boot protocol > might be manipulated too, before signing (who knows what people do > in the wild). Make sense. > > So having a sane, unconditional fallback COMMAND_LINE_SIZE from the > first kernel is a must, methinks. By greping for COMMAND_LINE_SIZE for different arch, I think 8K being the fallback, in general, is good for now and the future: alpha/include/uapi/asm/setup.h 4:#define COMMAND_LINE_SIZE 256 arm/include/uapi/asm/setup.h 19:#define COMMAND_LINE_SIZE 1024 avr32/include/uapi/asm/setup.h 14:#define COMMAND_LINE_SIZE 256 cris/include/uapi/asm/setup.h 4:#define COMMAND_LINE_SIZE 256 frv/include/uapi/asm/setup.h 15:#define COMMAND_LINE_SIZE 512 ia64/include/uapi/asm/setup.h 4:#define COMMAND_LINE_SIZE 2048 m32r/include/uapi/asm/setup.h 8:#define COMMAND_LINE_SIZE 512 m68k/include/uapi/asm/setup.h 14:#define COMMAND_LINE_SIZE 256 mips/include/uapi/asm/setup.h 4:#define COMMAND_LINE_SIZE 4096 parisc/include/uapi/asm/setup.h 4:#define COMMAND_LINE_SIZE 1024 powerpc/include/uapi/asm/setup.h 4:#define COMMAND_LINE_SIZE 2048 s390/include/uapi/asm/setup.h 9:#define COMMAND_LINE_SIZE 4096 um/include/asm/setup.h 8:#define COMMAND_LINE_SIZE 4096 x86/include/asm/setup.h 6:#define COMMAND_LINE_SIZE 2048 xtensa/include/uapi/asm/setup.h 14:#define COMMAND_LINE_SIZE 256 c6x/include/uapi/asm/setup.h 4:#define COMMAND_LINE_SIZE 1024 microblaze/include/uapi/asm/setup.h 14:#define COMMAND_LINE_SIZE 256 mn10300/include/uapi/asm/param.h 16:#define COMMAND_LINE_SIZE 256 score/include/uapi/asm/setup.h 4:#define COMMAND_LINE_SIZE 256 tile/include/uapi/asm/setup.h 18:#define COMMAND_LINE_SIZE 2048 arc/include/asm/setup.h 15:#define COMMAND_LINE_SIZE 256 arm64/include/uapi/asm/setup.h 24:#define COMMAND_LINE_SIZE 2048 -- 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/