From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 70159282F30; Mon, 17 Aug 2026 18:28:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786991285; cv=none; b=t9qD4OTszOtNBgivE/VKiU02RVxpmn01AcbQ+y3yWWLQ0H1QzFPGWvj9bU8TVFLhzydX8O6PoCJG+BByo1HfZ55rCu72XXhSKcKtRO8Ew4+ORG/a5KPK8M+kMBLd8+N65whrKFglMi5uRSvzqFuf+b625EDDhOUNPhH4ybJ1oXo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786991285; c=relaxed/simple; bh=AoVTIzk3jGmCg58mMb/LowghHt/XyzU6NK34w8QPPHQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=dhCf/BYlTItyWvOAPAgr1m5ihKxS7DCZceaQbfjRTQvnmGhym/oWFJGjeLcb87nnFqiT5XTcMkSurvfWXpyQYEIHwbu8nBqVavqVcAGt58kzcXSz9F3LPdWIke5/ENScWEbqlvxyKJUfXMkDabqdp1swOpjeGRHcRDVmA+0RU8E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=P4DvbLHY; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="P4DvbLHY" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BCEB91F000E9; Mon, 17 Aug 2026 18:28:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786991284; bh=PVtjT/hfRhRlJODdlOASejcjGNfWFR2Xaqt/rj6G1LI=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=P4DvbLHY8OF5GWUfPuY+r7quycQRLI28NnoRoEiXSxVOKqBdyFCN3nVbG+QMsUD8a yCqn/o0NNHQfu+hp/pm7zc3G4+A7XgxjCxOzXv9/dCovROu8lqGG3LijmlnrJhyctJ f4g3msBNzHdQWeIq07eoKGE9kFhLsiwJLrX68ODzelP/k58C2JnrJ6SjK7GpDGeIKh SpcAGU14WzpahfyuzT9PtPM+o9ZAiZLphkidUxBLxOES4wOHthve1Kd38NW0n0J+13 UiE9DJgi5J37vdgCWXRkVvDq0rp1KiGyYDcXHwBxojGQ4LYkkqzm+xIHXFxTsBe3WE QuSD5ZrDVoXHw== Date: Mon, 17 Aug 2026 21:27:50 +0300 From: Leon Romanovsky To: Logan Gunthorpe Cc: "Rafael J. Wysocki" , Len Brown , Saket Dumbre , Bjorn Helgaas , linux-acpi@vger.kernel.org, acpica-devel@lists.linux.dev, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, Lukas Wunner , "Natu, Mahesh" Subject: Re: [PATCH RFC 4/7] PCI/P2PDMA: Prefer providers with better HMAT performance Message-ID: <20260817182750.GD66924@unreal> References: <20260812-hmat-p2p-v1-0-75ac41380585@nvidia.com> <20260812-hmat-p2p-v1-4-75ac41380585@nvidia.com> <5e7eb09b-a47b-4cb5-8629-0ca5fa39f1f9@deltatee.com> <20260816123836.GC66924@unreal> <3dc699d8-a5d1-4100-b717-07fd0956e61d@deltatee.com> Precedence: bulk X-Mailing-List: linux-acpi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3dc699d8-a5d1-4100-b717-07fd0956e61d@deltatee.com> On Mon, Aug 17, 2026 at 10:09:42AM -0600, Logan Gunthorpe wrote: > > > On 2026-08-16 06:38, Leon Romanovsky wrote: > >> This feels backwards to me. If ACPI is kind enough to include > >> information on P2PDMA support then I feel like we should use it > >> exclusively. Not prioritize the old janky whitelists. > > > > Right now, there is no ACPI support, and I chose to prioritize > > existing systems that already have some form of support over an ACPI > > solution that does not yet exist. > But don't we know whether ACPI is advertising support now? Certainly if > ACPI indicates support we should use it above all other considerations > today. Otherwise fall back on the white lists. And that should always > work. Even on my old hardware because the ACPI on that machine doesn't > advertise support, so it should fall back on the whitelist. I see no > need to ever check the whitelist before checking ACPI. Definitely. This will be addressed in the next version. Thanks > > Logan