From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e32.co.us.ibm.com (e32.co.us.ibm.com [32.97.110.150]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e32.co.us.ibm.com", Issuer "Equifax" (verified OK)) by ozlabs.org (Postfix) with ESMTP id C0851679A6 for ; Wed, 6 Sep 2006 16:13:32 +1000 (EST) Received: from westrelay02.boulder.ibm.com (westrelay02.boulder.ibm.com [9.17.195.11]) by e32.co.us.ibm.com (8.13.8/8.12.11) with ESMTP id k866DTdF015165 for ; Wed, 6 Sep 2006 02:13:29 -0400 Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by westrelay02.boulder.ibm.com (8.13.6/8.13.6/NCO v8.1.1) with ESMTP id k866DTBF172752 for ; Wed, 6 Sep 2006 00:13:29 -0600 Received: from d03av02.boulder.ibm.com (loopback [127.0.0.1]) by d03av02.boulder.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id k866DSpF032586 for ; Wed, 6 Sep 2006 00:13:29 -0600 Message-ID: <44FE6700.8080504@us.ibm.com> Date: Tue, 05 Sep 2006 23:13:20 -0700 From: Haren Myneni MIME-Version: 1.0 To: michael@ellerman.id.au Subject: Re: [PATCH] kdump : Support kernels having 64k page size. References: <44FE15B0.3030909@in.ibm.com> <1157511577.3661.7.camel@localhost.localdomain> In-Reply-To: <1157511577.3661.7.camel@localhost.localdomain> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Cc: linuxppc-dev@ozlabs.org, "Sachin P. Sant" List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Michael Ellerman wrote: >On Wed, 2006-09-06 at 05:56 +0530, Sachin P. Sant wrote: > > >>The following kernel patch [ along with a patch to kexec tools posted >>seperately ] >>is required to generate proper core files using kdump on ppc64. >> >> > >Hi Sachin, > >Can you provide some more explanation? It's not clear to me why this is >necessary. > >thanks > > > At present we are doing the backup of 32K. Thus created one ELF PT_LOAD segment for this region. But, in the case of 64K page size, second segments starts at 32K and the first one is not page aligned. __ioremap() (crash_dump.c) getting failed if pfn = 0 which is the case for the second PT_LOAD segment. We did not hit this issue for 4K page size because the the first page (32K backup) is copied to second kernel memory and thus referencing with the second kernel pfn. Here the fix is, backup regions size is max(PAGE_SIZE, 32K) so that at least one page will be part of backup ELF segment. Drawback here is, we will end up 32K more for backup for 64K page size. It can also be fixed in copy_oldmem_page() (crash_dump.c), but first PT_LOAD segment is not page aligned: if (pfn > 0) vaddr = __ioremap(pfn << PAGE_SHIFT, PAGE_SIZE, 0); else vaddr = __va(pfn << PAGE_SHIFT); Thanks Haren >------------------------------------------------------------------------ > >_______________________________________________ >Linuxppc-dev mailing list >Linuxppc-dev@ozlabs.org >https://ozlabs.org/mailman/listinfo/linuxppc-dev >