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 2CE27CD5BB0 for ; Fri, 22 May 2026 17:59:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:References: List-Owner; bh=QvhytzGMgy3nE/I3M4lZRHo1Fz4WHKJA8K2mHNM+zQY=; b=ibDtALDUSky/LB Mo8ZS8YKW9H6M0Suevpxz/75UgLPRn9IgZdsNPmCNPIclqcv9AISfVrJngCeGkakmqw23VZDZSgWC m6g85fSXhLOdbm7JQ95OQiklu0vLCnnB98UNgyhMeOaBUuwNRxZsZ7PkM+Mq6Ty24Kuln4g1fRX04 JOF3jXodY9OJuVhgfduQRktF+qHOlY3Y4HwCGWSfkPC5medhaeU/DSRPkNuXeN76IU0VYcm5OTGRL CVnNqFkNgRzaLbOyxkWhbJ2knIWga8diO9XkNwCCcI+bHwVHuyhALmj395xIXRkxEL0U0eq7hbbsK ub56s4raxCMhplMRKoqw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wQU9N-0000000BcaS-32pX; Fri, 22 May 2026 17:59:09 +0000 Received: from sea.source.kernel.org ([172.234.252.31]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wQU9L-0000000BcYe-0ovG for kexec@lists.infradead.org; Fri, 22 May 2026 17:59:08 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with UTF8SMTP id 6A2A140D81; Fri, 22 May 2026 17:59:06 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with UTF8SMTPSA id 23DC41F000E9; Fri, 22 May 2026 17:59:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779472746; bh=QvhytzGMgy3nE/I3M4lZRHo1Fz4WHKJA8K2mHNM+zQY=; h=Date:From:To:Cc:Subject:In-Reply-To; b=R/lF87yYK3T8ZgihOcJLjT1tJ2iqucYpoTXz+lE+iNM8GsdPFgTHohAXTIRWiXCaq Z3sLJcXDGLxdXpbjd5vXsU6R9vl67LHiffd1HrCgb9F7RXCuMOOfdz7pnSMbp79xKx bqeV2FB/iwmC+djHEZ5mqJS5Do9oSrdFTfzKqDljYArEUikYmdVLSGNtDVRe2CbZXe nSlHxZCLg/t15FV7B3ebQdjPPEJOXYtquDgAXX27hU8eVFNYP8lGHAlA4FwFKLJOmb 9sPWoEQ7WIovdqVHFNJR3cl90/fD+OjTmJ5s3ncJReREDo+cltiTIVjISJ3mzjWVrW j+eMJNK+bTxAw== Date: Fri, 22 May 2026 12:59:05 -0500 From: Bjorn Helgaas To: David Matlack Cc: kexec@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-pci@vger.kernel.org, Adithya Jayachandran , Alexander Graf , Alex Williamson , Bjorn Helgaas , Chris Li , David Rientjes , Jacob Pan , Jason Gunthorpe , Jonathan Corbet , Josh Hilke , Leon Romanovsky , Lukas Wunner , Mike Rapoport , Parav Pandit , Pasha Tatashin , Pranjal Shrivastava , Pratyush Yadav , Saeed Mahameed , Samiullah Khawaja , Shuah Khan , Vipin Sharma , William Tu , Yi Liu Subject: Re: [PATCH v5 05/11] PCI: liveupdate: Keep bus numbers constant during Live Update Message-ID: <20260522175905.GA232400@bhelgaas> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260512184846.119396-6-dmatlack@google.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260522_105907_254999_7EE19417 X-CRM114-Status: GOOD ( 11.08 ) 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: , Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org On Tue, May 12, 2026 at 06:48:40PM +0000, David Matlack wrote: > ... > + * The PCI core guarantees that preserved devices can be identified by the same > + * bus, device, and function numbers for as long as they are preserved > + * (including across kexec). To accomplish this, the PCI core always inherits > + * the secondary and subordinate bus numbers assigned to bridges during scanning > + * if any device is preserved. This is true even on architectures that always > + * assign new bus numbers during scanning. The kernel assumes the previous > + * kernel established a sane bus topology across kexec. > + * > + * If a misconfigured or unconfigured bridge is encountered during enumeration > + * while there are preserved devices, itss secondary and subordinate bus numbers > + * will be cleared and devices below it will not be enumerated. s/itss/its/ > + * To keep things simple, inherit the secondary and subordinate bus numbers on > + * _all_ bridges if _any_ PCI devices are preserved (i.e. even bridges without > + * any downstream endpoints that were preserved). This avoids accidentally > + * assigning a bridge a new window that overlaps with a preserved device that is > + * downstream of a different bridge. s/i.e. even/i.e. even/ (remove extra space)