From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from out02.mta.xmission.com ([166.70.13.232]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1ZN2Jm-0002bR-5P for kexec@lists.infradead.org; Wed, 05 Aug 2015 17:17:30 +0000 From: ebiederm@xmission.com (Eric W. Biederman) References: <20150724011615.6834.79628.stgit@softrs> <55BF4B1F.9000602@hitachi.com> <877fpcfi2j.fsf@x220.int.ebiederm.org> <04EAB7311EE43145B2D3536183D1A84454926993@GSjpTKYDCembx31.service.hitachi.net> Date: Wed, 05 Aug 2015 12:10:06 -0500 In-Reply-To: <04EAB7311EE43145B2D3536183D1A84454926993@GSjpTKYDCembx31.service.hitachi.net> (=?utf-8?B?Iuays+WQiOiLseWujw==?= / =?utf-8?Q?KAWAI=EF=BC=8CHIDEHIRO=22's?= message of "Tue, 4 Aug 2015 11:41:14 +0000") Message-ID: <87io8tvez5.fsf@x220.int.ebiederm.org> MIME-Version: 1.0 Subject: Re: [RFC V2 PATCH 0/1] kexec: crash_kexec_post_notifiers boot option related fixes List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: =?utf-8?B?5rKz5ZCI6Iux5a6PIC8gS0FXQUnvvIxISURFSElSTw==?= Cc: "linux-mips@linux-mips.org" , Baoquan He , "kexec@lists.infradead.org" , "linux-kernel@vger.kernel.org" , HATAYAMA Daisuke , =?utf-8?B?5bmz5p2+6ZuF?= =?utf-8?B?5bezIC8gSElSQU1BVFXvvIxNQVNBTUk=?= , Daniel Walker , Andrew Morton , Ingo Molnar , Vivek Goyal Iuays+WQiOiLseWujyAvIEtBV0FJ77yMSElERUhJUk8iICA8aGlkZWhpcm8ua2F3YWkuZXpAaGl0 YWNoaS5jb20+IHdyaXRlczoKCj4gSGVsbG8sCj4KPiBUaGFua3MgZm9yIHRoZSByZXBseS4KPgo+ PiBGcm9tOiBFcmljIFcuIEJpZWRlcm1hbiBbbWFpbHRvOmViaWVkZXJtQHhtaXNzaW9uLmNvbV0K PiBbLi4uXQo+PiBBIHNwZWNpZmljIGhvb2sgZm9yIGEgdmVyeSBzcGVjaWZpYyBwdXJwb3NlIHdo ZW4gdGhlcmUgaXMgbm8gb3RoZXIgd2F5Cj4+IHdlIGNhbiBjb25zaWRlci4KPgo+IFNvLCBpcyBr bXNnX2R1bXAgbGlrZSBmZWF0dXJlIGFkbWlzc2libGU/Cj4KPj4gSWYgeW91IGRvbid0IGhhdmUg c29tZXRoaW5nIHRoYXQgZ2VuZXJhbGlzZXMgd2VsbCBpbnRvIGEgZ2VuZXJhbCBwdXJwb3NlCj4+ IG9wZXJhdGlvbiB0aGF0IGl0IG1ha2VzIHNlbnNlIGZvciBldmVyeW9uZSB0byBjYWxsIHlvdSBj YW4gYWx3YXlzIHVzZQo+PiB0aGUgd29ybGQncyBsYXJnZXN0IGFrYSB5b3UgY2FuIHJ1biBjb2Rl IGJlZm9yZSB0aGUgbmV3IGtlcm5lbCBzdGFydHMKPj4gdGhhdCBpcyBsb2FkZWQgd2l0aCBrZXhl Y19sb2FkLgo+Cj4gT25lIG9mIG91ciBwdXJwb3Nlcywgbm90aWZ5aW5nICJJJ20gZHlpbmciLCB3 b3VsZCBiZSBhY2hpZXZlZCBieSBwdXJnYXRvcnkKPiBjb2RlIHByb3ZpZGVkIGJ5IGtleGVjIGNv bW1hbmQgYXMgSSBzdGF0ZWQgYmVmb3JlLiAgU2luY2UgdGhlIHdheSBvZiB0aGUKPiBub3RpZmlj YXRpb24gd2lsbCBkaWZmZXIgZnJvbSBlYWNoIHZlbmRvciwgSSB0aGluayB3ZSBuZWVkIHRvIG1v ZGlmeQo+IHRoZSBwdXJnYXRvcnkgY29kZXMgcGx1Z2dhYmxlLiAgQWxzbywgSSB0aGluayB3ZSBu ZWVkIHNvbWUgcGFyYW1ldGVyCj4gcGFzc2luZyBtZWNoYW5pc20gdG8gdGhlIHB1cmdhdG9yeSBj b2RlLiAgRm9yIGV4YW1wbGUsIHBhc3NpbmcgdGhlIHBhbmljCj4gbWVzc2FnZSB2aWEgYm9vdCBw YXJhbWV0ZXIgdG8gc2F2ZSBpdCB0byBTRUwuICBBbHRob3VnaCBJJ20gbm90IHN1cmUKPiB3ZSBj YW4gZG8gdGhhdCAoSSd2ZSBub3QgaW52ZXN0aWdhdGVkIHdlbGwgeWV0KS4gIElzIHRoYXQgYWNj ZXB0YWJsZT8KCkkgdGhpbmsgdGhlIGFkZHJlc3Mgb2YgcGFuaWMgbWVzc2FnZSBpcyBhdmFpbGFi bGUgaW4gY3Jhc2ggbm90ZXMuICBJZgpub3QgdGhhdCBpcyB2ZXJ5IHJlYXNvbmFibGUgdG8gYWRk LgoKVXBkYXRpbmcgdGhlIFNFTCBmcm9tIHB1cmdhdG9yeSBhZnRlciBwdXJnYXRvcnkgaGFzIHZh bGlkYXRlZCB0aGUKY2hlY2tzdW1zIG9mIHRoZSBjcmFzaCBoYW5kbGluZyBjb2RlIGlzIGFjY2Vw dGFibGUuCgpBbGwgdGhhdCBpcyBkZXNpcmVkIGlzIHRvIHJ1biBhcyBsaXR0bGUgY29kZSBhcyBw b3NzaWJsZSBpbiBhIGtlcm5lbAp0aGF0IGlzIGtub3duIGJyb2tlbi4gIE9uY2UgdGhlIGNoZWNr c3VtcyBoYXZlIHZlcmlmaWVkIHRoaW5ncyBpbgpwdXJnYXRvcnkgeW91IHNob3VsZCBiZSBpbiBn b29kIHNoYXBlLCBhbmQgdGhlcmUgaXMgbm8gcG9zc2liaWxpdHkgb2YKcmVseWluZyBvbiBicm9r ZW4gaW5mcmFzdHJ1Y3R1cmUgYmVjYXVzZSB0aGF0IGNvZGUgc2ltcGx5IGlzIG5vdCBwcmVzZW50 CmluIHB1cmdhdG9yeS4KCldlIGFscmVhZHkgaGF2ZSBhIGZldyBlYXJseV9wcmludGsgc3R5bGUg ZHJpdmVycyBpbiBwdXJnYXRvcnkgYW5kIEkKZG9uJ3QgdGhlIGNvZGUgdG8gdXBkYXRlIHRoZSBT RUwgd291bGQgYmUgbXVjaCB3b3JzZS4KCk9uIHRoZSBmbGlwIHNpZGUgdGhlcmUgYXJlIGVub3Vn aCBmaXJtd2FyZSBidWdzIHRoYXQgSSBwZXJzb25hbGx5IHdvdWxkCm5vdCB3YW50IHRvIHJlbHkg b24gZmlybXdhcmUgY29kZSBydW5uaW5nIHByb3Blcmx5IHdoZW4gdGhlIG1hY2hpbmUgaXMKaW4g YSBrbm93biBicm9rZW4gc3RhdGUsIHNvIEkgZG9uJ3Qgd2FudCB0aGUgU0VMIHVwZGF0ZSB0byBi ZQp1bmNvbmRpdGlvbmFsLgoKRXJpYwoKCgpfX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fXwprZXhlYyBtYWlsaW5nIGxpc3QKa2V4ZWNAbGlzdHMuaW5mcmFkZWFk Lm9yZwpodHRwOi8vbGlzdHMuaW5mcmFkZWFkLm9yZy9tYWlsbWFuL2xpc3RpbmZvL2tleGVjCg== From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Wed, 05 Aug 2015 19:17:00 +0200 (CEST) Received: from out02.mta.xmission.com ([166.70.13.232]:37974 "EHLO out02.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by eddie.linux-mips.org with ESMTP id S27012329AbbHERQ53fgvg convert rfc822-to-8bit (ORCPT ); Wed, 5 Aug 2015 19:16:57 +0200 Received: from in01.mta.xmission.com ([166.70.13.51]) by out02.mta.xmission.com with esmtps (TLS1.2:DHE_RSA_AES_128_CBC_SHA1:128) (Exim 4.82) (envelope-from ) id 1ZN2J7-0001bZ-LM; Wed, 05 Aug 2015 11:16:49 -0600 Received: from 97-119-22-40.omah.qwest.net ([97.119.22.40] helo=x220.int.ebiederm.org.xmission.com) by in01.mta.xmission.com with esmtpsa (TLS1.2:DHE_RSA_AES_128_CBC_SHA1:128) (Exim 4.82) (envelope-from ) id 1ZN2J6-0003Tb-Ai; Wed, 05 Aug 2015 11:16:49 -0600 From: ebiederm@xmission.com (Eric W. Biederman) To: =?utf-8?B?5rKz5ZCI6Iux5a6PIC8gS0FXQUnvvIxISURFSElSTw==?= Cc: Vivek Goyal , Andrew Morton , "linux-mips\@linux-mips.org" , Baoquan He , "kexec\@lists.infradead.org" , "linux-kernel\@vger.kernel.org" , "HATAYAMA Daisuke" , =?utf-8?B?5bmz5p2+6ZuF?= =?utf-8?B?5bezIC8gSElSQU1BVFXvvIxNQVNBTUk=?= , Daniel Walker , "Ingo Molnar" References: <20150724011615.6834.79628.stgit@softrs> <55BF4B1F.9000602@hitachi.com> <877fpcfi2j.fsf@x220.int.ebiederm.org> <04EAB7311EE43145B2D3536183D1A84454926993@GSjpTKYDCembx31.service.hitachi.net> Date: Wed, 05 Aug 2015 12:10:06 -0500 In-Reply-To: <04EAB7311EE43145B2D3536183D1A84454926993@GSjpTKYDCembx31.service.hitachi.net> (=?utf-8?B?Iuays+WQiOiLseWujw==?= / =?utf-8?Q?KAWAI=EF=BC=8CHIDEHIRO=22's?= message of "Tue, 4 Aug 2015 11:41:14 +0000") Message-ID: <87io8tvez5.fsf@x220.int.ebiederm.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT X-XM-AID: U2FsdGVkX18RPZC33dA55LTTOfLKiKElNPZ8H7AUiII= X-SA-Exim-Connect-IP: 97.119.22.40 X-SA-Exim-Mail-From: ebiederm@xmission.com Subject: Re: [RFC V2 PATCH 0/1] kexec: crash_kexec_post_notifiers boot option related fixes X-SA-Exim-Version: 4.2.1 (built Wed, 24 Sep 2014 11:00:52 -0600) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 48605 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: ebiederm@xmission.com Precedence: bulk List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-Id: linux-mips X-List-ID: linux-mips List-subscribe: List-owner: List-post: List-archive: X-list: linux-mips "河合英宏 / KAWAI，HIDEHIRO" writes: > Hello, > > Thanks for the reply. > >> From: Eric W. Biederman [mailto:ebiederm@xmission.com] > [...] >> A specific hook for a very specific purpose when there is no other way >> we can consider. > > So, is kmsg_dump like feature admissible? > >> If you don't have something that generalises well into a general purpose >> operation that it makes sense for everyone to call you can always use >> the world's largest aka you can run code before the new kernel starts >> that is loaded with kexec_load. > > One of our purposes, notifying "I'm dying", would be achieved by purgatory > code provided by kexec command as I stated before. Since the way of the > notification will differ from each vendor, I think we need to modify > the purgatory codes pluggable. Also, I think we need some parameter > passing mechanism to the purgatory code. For example, passing the panic > message via boot parameter to save it to SEL. Although I'm not sure > we can do that (I've not investigated well yet). Is that acceptable? I think the address of panic message is available in crash notes. If not that is very reasonable to add. Updating the SEL from purgatory after purgatory has validated the checksums of the crash handling code is acceptable. All that is desired is to run as little code as possible in a kernel that is known broken. Once the checksums have verified things in purgatory you should be in good shape, and there is no possibility of relying on broken infrastructure because that code simply is not present in purgatory. We already have a few early_printk style drivers in purgatory and I don't the code to update the SEL would be much worse. On the flip side there are enough firmware bugs that I personally would not want to rely on firmware code running properly when the machine is in a known broken state, so I don't want the SEL update to be unconditional. Eric