From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mercury.realtime.net ([205.238.132.86]) by bombadil.infradead.org with esmtp (Exim 4.68 #1 (Red Hat Linux)) id 1KyRhU-0005od-MQ for kexec@lists.infradead.org; Fri, 07 Nov 2008 13:48:36 +0000 In-Reply-To: <18687.62202.333736.269891@drongo.ozlabs.ibm.com> References: <18687.61506.924500.411952@drongo.ozlabs.ibm.com> <18687.62202.333736.269891@drongo.ozlabs.ibm.com> Mime-Version: 1.0 (Apple Message framework v624) Message-Id: From: Milton Miller Subject: Re: [PATCH 3/3] powerpc/ppc64/kdump: better flag for running relocatable Date: Fri, 7 Nov 2008 07:52:31 -0600 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: kexec-bounces@lists.infradead.org Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Paul Mackerras Cc: Michael Ellerman , Ben Herrenschmidt , Simon Horman , kexec@lists.infradead.org, linuxppc-dev@ozlabs.org On Oct 22, 2008, at 10:43 PM, Paul Mackerras wrote: > Paul Mackerras writes: >> Milton Miller writes: >>> Move the flag to 0x5c, 1 word before the secondary cpu entry point at >>> 0x60. Use the copy at address 0 not the one in the base kernel >>> image to >>> make it easier on kexec-tools. >> >> Why is it easier on kexec-tools? Doesn't kexec-tools know where it >> put the kernel? The archictecture code calls cross-platform code to identify what is loaded. It isn't specified if this is a shared mmap or a read into a buffer. >> >> I'd much rather keep the flag inside the kdump kernel image, rather >> than having kexec/kdump start using random fixed locations outside the >> new kernel image. > > In fact the cliching argument is that when the kernel is loaded by OF > or yaboot, we have no way to tell what will be at location 0x5c, > whereas we know that the word at offset 0x5c in the kernel image will > have been initialized to 0. So we had better put the flag inside the > kernel image. Well, prom_init will copy the 256 bytes to 0 before the code checks that location. However, there is an arguement for using the same code from an epapr or book-e relocatable, and that would need it at 0. And today the kexec tool does not do a shared mmap. Since the change has been made, I will make a new patch for kexec-tools. milton _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec