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 X-Spam-Level: X-Spam-Status: No, score=0.2 required=3.0 tests=DKIM_ADSP_ALL,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EDAD2C28CF6 for ; Wed, 1 Aug 2018 14:16:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5636B208A4 for ; Wed, 1 Aug 2018 14:16:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=natalenko.name header.i=@natalenko.name header.b="rEFSlUGn" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5636B208A4 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=natalenko.name Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389580AbeHAQCn (ORCPT ); Wed, 1 Aug 2018 12:02:43 -0400 Received: from vulcan.natalenko.name ([104.207.131.136]:53346 "EHLO vulcan.natalenko.name" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389344AbeHAQCm (ORCPT ); Wed, 1 Aug 2018 12:02:42 -0400 Received: from mail.natalenko.name (vulcan.natalenko.name [IPv6:fe80::5400:ff:fe0c:dfa0]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by vulcan.natalenko.name (Postfix) with ESMTPSA id DD6B73BD493; Wed, 1 Aug 2018 16:16:42 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=natalenko.name; s=dkim-20170712; t=1533133003; h=from:from:sender: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:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ZxBoa0v1qT37CRtjEc5PskihmZMdBAYz3QNxU+zUUac=; b=rEFSlUGnI/bv+qbyIopfKw20bWMUsxUofEjBJ94qQNJ/yG3EwUHUpr6HjGwJIxOrXrn9HW hTpaNRfii0MCJkvwCIsyQHNeL7cvbUcy5ti8DYOHAr1XXjpMy63Ee/ILQ2OIfZY7mc06rP 59acHBOBElqtYw5ME6xlrUBHbeylHUA= DMARC-Filter: OpenDMARC Filter v1.3.2 vulcan.natalenko.name DD6B73BD493 Authentication-Results: vulcan.natalenko.name; dmarc=fail (p=none dis=none) header.from=natalenko.name MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Wed, 01 Aug 2018 16:16:42 +0200 From: Oleksandr Natalenko To: Prarit Bhargava Cc: bp@alien8.de, linux-edac@vger.kernel.org, linux-kernel@vger.kernel.org, sironi@amazon.de, stable@vger.kernel.org, tony.luck@intel.com Subject: Re: [PATCH v2] arch/x86: Fix boot_cpu_data.microcode version output In-Reply-To: References: Message-ID: <0a4c663887ecc1672d9927ed7256485b@natalenko.name> X-Sender: oleksandr@natalenko.name User-Agent: Roundcube Webmail/1.3.6 ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=natalenko.name; s=arc-20170712; t=1533133003; h=from:from:sender: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:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ZxBoa0v1qT37CRtjEc5PskihmZMdBAYz3QNxU+zUUac=; b=NafF3XKP1RywXS+WcHvFtlY0cxhfZwEle7QLWNXTjfiC3hedFFvEdRhGYN/91MLxupdcuU BK8JDatiO/HnrYgWCSgMciQHWcFEJD6TTIgLrHZvm/Oc4QIzoIstXZo4Qu+9NK8yKo8x6v ZKLkpqoUTSOa57FofSifxyH/HC92TBU= ARC-Seal: i=1; s=arc-20170712; d=natalenko.name; t=1533133003; a=rsa-sha256; cv=none; b=XAtfVI3kdoYN5Ebhxu36rUl0lGZC+Cp/OLFhnslPAr0lU8trOBD2IzmPWzhvGoQg3cEAmF6/FKNNhBuTDQZ7LlZXBOjyeoSB7OUI0uL1eUwnupDqkBFy87IbI6Wsy6HI5gY0dFqnkeo+8vDOGzXe7Ji5Flm0r5wdmSXgRSrlQ5I= ARC-Authentication-Results: i=1; vulcan.natalenko.name; auth=pass smtp.auth=oleksandr@natalenko.name smtp.mailfrom=oleksandr@natalenko.name Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi. On 01.08.2018 13:38, Prarit Bhargava wrote: >> After this patch, do we preserve an original microcode version >> somewhere? If no, >> why? Sometimes it is useful while debugging another crash because of >> faulty >> microcode. >> > Interesting, and thanks for bringing this up. Oleksandr, under what > circumstances would you want to know what the old version was. AFAICS > it is no > longer running and should not have an impact on the system? Once the kernel log does not contain a printout regarding updated microcode anymore (because the log buffer is limited in size and can be overwritten) and once you have a vmcore, it is handy to use boot_cpu_data to compare the microcode version with the per-CPU value to find out that is was updated at all. Or, maybe, that can be inspected in another way now? -- Oleksandr Natalenko (post-factum)