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 lists1p.gnu.org (lists1p.gnu.org [209.51.188.17]) (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 880B7CD4F21 for ; Wed, 13 May 2026 14:26:16 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1wNAXE-0003xF-7T; Wed, 13 May 2026 10:26:05 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1wNAWx-0003v8-JM for qemu-arm@nongnu.org; Wed, 13 May 2026 10:25:49 -0400 Received: from sea.source.kernel.org ([172.234.252.31]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1wNAWv-0007Mi-Bi for qemu-arm@nongnu.org; Wed, 13 May 2026 10:25:47 -0400 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id D8EF343B44; Wed, 13 May 2026 14:25:40 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5D607C4AF0B; Wed, 13 May 2026 14:25:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778682340; bh=OBmUeu+JTmeLVp+hLNb3VMMtuET3zSq0zHFW5yCb31s=; h=Date:From:To:Cc:In-Reply-To:References:Subject:From; b=nk8zLEQHAZM9nyc3wLM0N3fyLuBaFrE9V3pj0xou8HpnYodelXGhi2wtf8KVmIz/f 90COB1euRofSnF21e3w3WhqL2UXpLelias8uySFtoNDHDG1D2DFqEhUlZ++4BnoD2g /U7XYnMO7PcFyLHqPU4UJGVgzCOJj8bDDPNUj1MGMIFymllrAqLZ27Z7RfLT5p2cZ9 7nCVQCdBIQVaNvTMcujZugSzQk/dKyI1J0wvveHwFHSkaFboPRkvdHiVlXPvAI/oQ1 2YzoKv323xcJpFFhaKEVD+Tk2d6PDtZ9jAqoRwTQYnu8wJXr6cVaNyqJegNb9b5gjY D7Sm1sn4VROoQ== Received: from phl-compute-01.internal (phl-compute-01.internal [10.202.2.41]) by mailfauth.phl.internal (Postfix) with ESMTP id 6CB46F4006F; Wed, 13 May 2026 10:25:39 -0400 (EDT) Received: from phl-imap-14 ([10.202.2.87]) by phl-compute-01.internal (MEProxy); Wed, 13 May 2026 10:25:39 -0400 X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeefhedrtddtgdduvdegkeelucetufdoteggodetrf dotffvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfurfetoffkrfgpnffqhgenuceu rghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmnecujf gurhepofggfffhvfevkfgjfhfutgfgsehtjeertdertddtnecuhfhrohhmpedftehrugcu uehivghshhgvuhhvvghlfdcuoegrrhgusgeskhgvrhhnvghlrdhorhhgqeenucggtffrrg htthgvrhhnpedvueehiedtvedtleekuddutefgffdtleetfeetveejveejieehfefhjeei jeefudenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpe grrhguodhmvghsmhhtphgruhhthhhpvghrshhonhgrlhhithihqdduieejtdehtddtjeel qdeffedvudeigeduhedqrghruggspeepkhgvrhhnvghlrdhorhhgseifohhrkhhofhgrrh gurdgtohhmpdhnsggprhgtphhtthhopeduvddpmhhouggvpehsmhhtphhouhhtpdhrtghp thhtohepuggvvhgvlhesvggukhdvrdhgrhhouhhpshdrihhopdhrtghpthhtohepmhgrrh gtvghlrdgrphhfvghlsggruhhmsehgmhgrihhlrdgtohhmpdhrtghpthhtohepphgvthgv rhdrmhgrhiguvghllheslhhinhgrrhhordhorhhgpdhrtghpthhtohepqhgvmhhuqdgrrh hmsehnohhnghhnuhdrohhrghdprhgtphhtthhopehqvghmuhdquggvvhgvlhesnhhonhhg nhhurdhorhhgpdhrtghpthhtoheprghlvgigrdifihhllhhirghmshhonhesnhhvihguih grrdgtohhmpdhrtghpthhtohepjhhgghesnhhvihguihgrrdgtohhmpdhrtghpthhtohep shhkohhlohhthhhumhhthhhosehnvhhiughirgdrtghomhdprhgtphhtthhopehtuggrvh gvsehnvhhiughirgdrtghomh X-ME-Proxy: Feedback-ID: ice86485a:Fastmail Received: by mailuser.phl.internal (Postfix, from userid 501) id 4D81EC4006E; Wed, 13 May 2026 10:25:39 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface MIME-Version: 1.0 Date: Wed, 13 May 2026 16:25:10 +0200 From: "Ard Biesheuvel" To: "Alex Williamson" , "Michael S. Tsirkin" , "Alex Williamson" Cc: "Tushar Dave" , =?UTF-8?Q?C=C3=A9dric_Le_Goater?= , "devel@edk2.groups.io" , qemu-devel@nongnu.org, "Jason Gunthorpe" , "Shameer Kolothum" , qemu-arm@nongnu.org, "Peter Maydell" , marcel.apfelbaum@gmail.com Message-Id: In-Reply-To: <382877be-edad-4eca-a646-a75e1654747f@app.fastmail.com> References: <20260508183717.193630-1-tdave@nvidia.com> <22cf37c2-b2b1-40db-b8b7-393b6c36a921@app.fastmail.com> <20260512170650.4551c9f6@nvidia.com> <20260512191140-mutt-send-email-mst@kernel.org> <382877be-edad-4eca-a646-a75e1654747f@app.fastmail.com> Subject: Re: [edk2-devel] [RFC PATCH 0/8] hw/arm/virt, hw/pci: PCI pre-enumeration and fixed BAR allocation Content-Type: text/plain Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=172.234.252.31; envelope-from=ardb@kernel.org; helo=sea.source.kernel.org X-Spam_score_int: -24 X-Spam_score: -2.5 X-Spam_bar: -- X-Spam_report: (-2.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.445, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-arm@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-arm-bounces+qemu-arm=archiver.kernel.org@nongnu.org Sender: qemu-arm-bounces+qemu-arm=archiver.kernel.org@nongnu.org On Wed, 13 May 2026, at 01:57, Alex Williamson wrote: > On Tue, May 12, 2026, at 5:12 PM, Michael S. Tsirkin wrote: >> On Tue, May 12, 2026 at 05:06:50PM -0600, Alex Williamson wrote: >>> If we agree that homogeneous hierarchies (no mixing of EA and >>> programmable BARs) is a reasonable constraint, and possibly extend >>> that to homogeneous per host bridge to simplify the CRS mapping, we >>> have the following work items: >>> >>> * Extend Linux EA support to program bridge apertures for >>> subordinate homogeneous EA hierarchies. >>> >>> * Develop options to virtualize programmable BARs as EA for vfio- >>> pci devices, if not generically for the benefit of testing. >>> >>> * Implement a way to poke holes in the VM address space and plumb >>> through to account for addresses used by EA devices. >>> >>> * Provide those same ranges to the guest via CRS (but not via DT to >>> EDK2), or alternatively expose them through additional PXB host >>> bridges. >>> >>> Does that shape roughly seem accurate? Are there additional gaps >>> I've missed? Thanks, >> >> just one question why not do it in firmware so windows is thinkably >> also handled? > > I suppose someone could chime in if they have a similar requirement > for Windows guests. Otherwise, the incremental effort to extend Linux > EA support seems smaller, though I also don't know what, if any > support Windows has for EA to bother. Regardless, improving Linux EA > support might help elsewhere and doesn't preclude edk2 support in the > future. Thanks, > If EA is too much of a hassle to implement, another avenue that you might explore is EFI_INCOMPATIBLE_PCI_DEVICE_SUPPORT_PROTOCOL in edk2, which can be implemented by the platform to inform the PCI core about non-PCI compliant devices that have special requirements. While it is supposed to support this use case too, the PCI resource allocation code in EDK2 currently does not correctly support fixed resources that are reported by this protocol, but getting that fixed (and implementing the protocol in your firmware) might be a shorter path to getting this hardware supported under any OS (assuming EFI boot) than EA.