From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 29222C433FE for ; Fri, 30 Sep 2022 16:51:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=WwXhAT7BvI5xEiI6UW/H1T6I0y/AF6oAZpF8JR3+fnQ=; b=p/C91Guoqr91F5 b/mLzKIoVcrDliuSQlEKhw2rFM7a2NXxZiS6MT2RRNkNgdETcQfbkXH3EUxEuzMU64mlwqiFnGLnn uiB8sgUCNHDCNF0FNu3nhi768MtqCHI3kYzFsttBaVh7VX53YgFpojFSrAvD5m96rgDR5TM/imcoj cKFKGChOKFOwqaVQd/HsTkN6EcxAgguxMDoe76dUG2u2mKLz3qdql5EkOMYvRgXAN/+uT5q2MvZf/ MkAmvHFd4tJJc01Y/MgxSEiNUyHztvz4akxG7QuIHPLj1fPlV01ev/D9TbNGTM10X8BFZk0fa5z7m obPXFrl2j7vlPET83Q/g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oeJEE-00AfrM-ES; Fri, 30 Sep 2022 16:51:10 +0000 Received: from mail.skyhub.de ([2a01:4f8:190:11c2::b:1457]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oeJE9-00Afpq-50 for kexec@lists.infradead.org; Fri, 30 Sep 2022 16:51:09 +0000 Received: from zn.tnic (p200300ea9733e70a329c23fffea6a903.dip0.t-ipconnect.de [IPv6:2003:ea:9733:e70a:329c:23ff:fea6:a903]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 521CF1EC04DA; Fri, 30 Sep 2022 18:50:59 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1664556659; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=tP9Z9kALkJplQ//X4pAwQj/9u9C0dERnBu4DmkUwjxM=; b=c5NyopsCGhoBd1uFmWvBwlikJDwE9xijsQuDUsK2MmV90jGTOcm63idZOnV6Lj4D4e39P9 v61pX3A4xPk6l3MtmFUWpfWQtk+mOYlIUb/P9iMve1okkWXLYa8XM4GmjXSHmiQ3q/Ddaa ZeUxI7kH5Q5VUgJQuc7SssTEQA+hucI= Date: Fri, 30 Sep 2022 18:50:55 +0200 From: Borislav Petkov To: Eric DeVolder , Oscar Salvador , Andrew Morton , david@redhat.com Cc: linux-kernel@vger.kernel.org, x86@kernel.org, kexec@lists.infradead.org, ebiederm@xmission.com, dyoung@redhat.com, bhe@redhat.com, vgoyal@redhat.com, tglx@linutronix.de, mingo@redhat.com, dave.hansen@linux.intel.com, hpa@zytor.com, nramas@linux.microsoft.com, thomas.lendacky@amd.com, robh@kernel.org, efault@gmx.de, rppt@kernel.org, sourabhjain@linux.ibm.com, linux-mm@kvack.org Subject: Re: [PATCH v12 7/7] x86/crash: Add x86 crash hotplug support Message-ID: References: <20220909210509.6286-1-eric.devolder@oracle.com> <20220909210509.6286-8-eric.devolder@oracle.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220930_095105_390966_1BB04BDB X-CRM114-Status: GOOD ( 22.89 ) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list 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" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org On Fri, Sep 30, 2022 at 10:36:49AM -0500, Eric DeVolder wrote: > > Your help text talks about System RAM entries in /proc/iomem which means > > that those entries are present somewhere in the kernel and you can read > > them out and do the proper calculations dynamically instead of doing the > > static CONFIG_NR_CPUS_DEFAULT + CONFIG_CRASH_MAX_MEMORY_RANGES thing. > > The intent is to compute the max size buffer needed to contain a maximum > populated elfcorehdr, which is primarily based on the number of CPUs and > memory regions. Thus far I (and others involved) have not found a kernel > method to determine the maximum number of memory regions possible (if you > are aware of one, please let me know!). Thus CONFIG_CRASH_MAX_MEMORY_RANGES > was born (rather borrowed from kexec-tools). Let's ask some mm folks. mm folks, is there a way to enumerate all the memory regions a machine has? It looks to me like register_memory_resource() in mm/memory_hotplug.c does register the resource so there should be a way to count that list of resources or at least maintain a count somewhere so that kexec/crash code can know how big its elfcodehdr buffer should be instead of doing a clumsy Kconfig item where people would need to guess... Hmm. > > +#ifdef CONFIG_CRASH_MAX_MEMORY_RANGES > So I think the use of CONFIG_CRASH_MAX_MEMORY_RANGES is not correct; it > still needs to be based on the cpu or memory hotplug options. You're kidding, right? +config CRASH_MAX_MEMORY_RANGES + depends on CRASH_DUMP && KEXEC_FILE && (HOTPLUG_CPU || MEMORY_HOTPLUG) ^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > > @@ -622,6 +622,15 @@ static int __init crash_save_vmcoreinfo_init(void) > > subsys_initcall(crash_save_vmcoreinfo_init); > > #if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_MEMORY_HOTPLUG) > > + > > +void __weak *arch_map_crash_pages(unsigned long paddr, unsigned long size) > > +{ > > + return NULL; > > +} > > + > > +void __weak arch_unmap_crash_pages(void **ptr) { } > > +void __weak arch_crash_handle_hotplug_event(struct kimage *image, unsigned int hp_action) { } > > + > I was asked by Baoquan He to eliminate the use of __weak Because? -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec