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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (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 169BEC61D85 for ; Tue, 21 Nov 2023 02:40:36 +0000 (UTC) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=ellerman.id.au header.i=@ellerman.id.au header.a=rsa-sha256 header.s=201909 header.b=oWW1QkZz; dkim-atps=neutral Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4SZ7sH1rBYz3dBq for ; Tue, 21 Nov 2023 13:40:35 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=ellerman.id.au header.i=@ellerman.id.au header.a=rsa-sha256 header.s=201909 header.b=oWW1QkZz; dkim-atps=neutral Received: from gandalf.ozlabs.org (mail.ozlabs.org [IPv6:2404:9400:2221:ea00::3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4SZ5mh0Jcbz3bcJ for ; Tue, 21 Nov 2023 12:06:28 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ellerman.id.au; s=201909; t=1700528778; bh=a1oDztLoqCcees2awcLjiaomu8bb0ZU8fyFhFCJHT4Y=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=oWW1QkZze+kq8dXCMwzP9xmtsiBPKW/hq5HCmqkQq67lD/f/fkTpd/U8FMenAoeLl J1jHM3vpiqO6+SZ8oTRmtfdXJh/kl4ccKcHX93lWk6Fma5jYDgW+qHGJ9G1c3wWEWD 7wf1DanMy/hBgRK5n8rOjbSflcR7GKDrM1MFeaKqqOQQlvcOByEoS81ZnH8kRCiVRW Sitlo5WEKfvTkyRjxvm6DcVAjGDg3Q0vGj0AeAoNLiUIP8cnYZXsQFMSjypuMtAUTc 2SzMvY2J7oKCYA9k2z45igYP3WpwqyzkKDLwx57xpFYnZrXJC9CTNoEySocvsKn9xW xnByzdpmU0vWQ== Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mail.ozlabs.org (Postfix) with ESMTPSA id 4SZ5mB3sycz4wd7; Tue, 21 Nov 2023 12:06:02 +1100 (AEDT) From: Michael Ellerman To: Ignat Korchagin , eric.devolder@oracle.com Subject: Re: Potential config regression after 89cde455 ("kexec: consolidate kexec and crash options into kernel/Kconfig.kexec") In-Reply-To: References: Date: Tue, 21 Nov 2023 12:05:59 +1100 Message-ID: <87y1er6hl4.fsf@mail.lhotse> MIME-Version: 1.0 Content-Type: text/plain X-Mailman-Approved-At: Tue, 21 Nov 2023 13:39:48 +1100 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: chenhuacai@kernel.org, linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, Peter Zijlstra , catalin.marinas@arm.com, linus.walleij@linaro.org, dave.hansen@linux.intel.com, linux-mips@vger.kernel.org, James Bottomley , dalias@libc.org, hpa@zytor.com, linux-riscv@lists.infradead.org, will@kernel.org, kernel@xen0n.name, tsi@tuyoix.net, linux-s390@vger.kernel.org, agordeev@linux.ibm.com, rmk+kernel@armlinux.org.uk, paulmck@kernel.org, ysato@users.sourceforge.jp, kernel-team , deller@gmx.de, x86@kernel.org, linux@armlinux.org.uk, paul.walmsley@sifive.com, Ingo Molnar , geert@linux-m68k.org, hbathini@linux.ibm.com, samitolvanen@google.com, ojeda@kernel.org, juerg.haefliger@canonical.com, borntraeger@linux.ibm.com, frederic@kernel.org, arnd@arndb.de, mhiramat@kernel.org, Ard Biesheuvel , thunder.leizhen@huawei.com, aou@eecs.berkeley.edu, keescook@chromium.org, go r@linux.ibm.com, anshuman.khandual@arm.com, hca@linux.ibm.com, xin3.li@intel.com, npiggin@gmail.com, konrad.wilk@oracle.com, linux-m68k@lists.linux-m68k.org, Borislav Petkov , loongarch@lists.linux.dev, glaubitz@physik.fu-berlin.de, Thomas Gleixner , ziy@nvidia.com, linux-arm-kernel@lists.infradead.org, boris.ostrovsky@oracle.com, tsbogend@alpha.franken.de, sebastian.reichel@collabora.com, bhe@redhat.com, linux-parisc@vger.kernel.org, Greg KH , kirill.shutemov@linux.intel.com, ndesaulniers@google.com, linux-kernel , sourabhjain@linux.ibm.com, palmer@dabbelt.com, svens@linux.ibm.com, tj@kernel.org, Andrew Morton , linuxppc-dev@lists.ozlabs.org, masahiroy@kernel.org, rppt@kernel.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Ignat Korchagin writes: > Good day! > > We have recently started to evaluate Linux 6.6 and noticed that we > cannot disable CONFIG_KEXEC anymore, but keep CONFIG_CRASH_DUMP > enabled. It seems to be related to commit 89cde455 ("kexec: > consolidate kexec and crash options into kernel/Kconfig.kexec"), where > a CONFIG_KEXEC dependency was added to CONFIG_CRASH_DUMP. > > In our current kernel (Linux 6.1) we only enable CONFIG_KEXEC_FILE > with enforced signature check to support the kernel crash dumping > functionality and would like to keep CONFIG_KEXEC disabled for > security reasons [1]. > > I was reading the long commit message, but the reason for adding > CONFIG_KEXEC as a dependency for CONFIG_CRASH_DUMP evaded me. And I > believe from the implementation perspective CONFIG_KEXEC_FILE should > suffice here (as we successfully used it for crashdumps on Linux 6.1). > > Is there a reason for adding this dependency or is it just an > oversight? Would some solution of requiring either CONFIG_KEXEC or > CONFIG_KEXEC_FILE work here? I don't actually see any reason for CRASH_DUMP to depend on KEXEC or KEXEC_FILE. None of the old CRASH_DUMP symbols depended on KEXEC AFAICS. Using something like: $ git diff 89cde455..95d1fef5 | grep -A 3 "^-.*config CRASH_DUMP" It's reasonable to want to build a kernel that supports CRASH_DUMP (ie. can be a dump kernel), but doesn't support kexec and requires a regular reboot. Though I doubt anyone does that in practice? cheers