From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from ale.deltatee.com (ale.deltatee.com [204.191.154.188]) (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 C8D1444AB99; Mon, 17 Aug 2026 16:09:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=204.191.154.188 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786982998; cv=none; b=UbnhwUHAjrbWrpT/ANWuxYAaVUkQw7nf/owt4w7IvFOurT8KkiYm1auzvfvYWj0hJLEGzPmTDXrW+xEbqT9AXTSQm6AXBq5rVmwBLeWfgxbiDhJrT1yLmXZzKYh7By096x3T87FexpoYrKNfxZOzbnpEmP3Y4T5f6BW1rAOMOSc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786982998; c=relaxed/simple; bh=0JL1/m7zpkpcy4wimsu+LK6Gqv2lsBXTfkvhd5FuNfk=; h=Message-ID:Date:MIME-Version:To:Cc:References:From:In-Reply-To: Content-Type:Subject; b=BFyNWsZLcrVMV5PQubugo7vdqS53gX8yJi8h0cNQYvqRU+VetKhRliBMi++k6somnKk9KOe/otLt7wYi1zOtevv5lRwxs3VejyT8FOsJ88D45DEa4D8v4EsYHaQWJ1+ffOQVPLR40hTIqlMWi+o7A7omuL2PugCBJ8qyWdpS4Lg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=deltatee.com; spf=pass smtp.mailfrom=deltatee.com; dkim=pass (2048-bit key) header.d=deltatee.com header.i=@deltatee.com header.b=NI9ABd8m; arc=none smtp.client-ip=204.191.154.188 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=deltatee.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=deltatee.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=deltatee.com header.i=@deltatee.com header.b="NI9ABd8m" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=deltatee.com; s=20200525; h=Subject:In-Reply-To:From:References:Cc:To: MIME-Version:Date:Message-ID:content-disposition; bh=Zsh2gTWUzN2dIhEO6xqGrM+bze4sMML+mg2E1OVs7pk=; b=NI9ABd8m7T1nCyAHna8FtBxhn2 EH6RmBtXDiZH7t7Z7ZBbwNtvT1+3FDOwwzIycpbWNTRDGnB0qgsA9Y3Vl+4mRAI1x46Gu7tuGWujs QIdxouyOv0spyBru4mfe9m2wn+KPtUd/4o4ivqXFAwYS3jDiAgpuNINLxlrVoE9yIjYW8UKlg0+fX RTIvwrLCG5x0Fo8E4f15MMC7As1+H5rj8DxIKfkgPj9GxTFiBDmE+Ks6v+ClDQdAWof+5b7BaxG28 YzuqQks94UO2Gkj7Ojs0ymQRradQBzrm2mNpCuSAsHU4cA2SGy5gxmT7xdfCtvnDoH4NbGpIcIZbC 6v9/DKOA==; Received: from guinness.priv.deltatee.com ([172.16.1.162]) by ale.deltatee.com with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.98.2) (envelope-from ) id 1wvzuK-0000000029y-0Y4O; Mon, 17 Aug 2026 10:09:52 -0600 Message-ID: <3dc699d8-a5d1-4100-b717-07fd0956e61d@deltatee.com> Date: Mon, 17 Aug 2026 10:09:42 -0600 Precedence: bulk X-Mailing-List: linux-acpi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird To: Leon Romanovsky 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" 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> Content-Language: en-CA From: Logan Gunthorpe In-Reply-To: <20260816123836.GC66924@unreal> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 172.16.1.162 X-SA-Exim-Rcpt-To: leon@kernel.org, rafael@kernel.org, lenb@kernel.org, saket.dumbre@intel.com, bhelgaas@google.com, linux-acpi@vger.kernel.org, acpica-devel@lists.linux.dev, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, lukas@wunner.de, mahesh.natu@intel.com X-SA-Exim-Mail-From: logang@deltatee.com X-Spam-Level: Subject: Re: [PATCH RFC 4/7] PCI/P2PDMA: Prefer providers with better HMAT performance X-SA-Exim-Version: 4.2.1 (built Sun, 23 Feb 2025 07:57:16 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) 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. Logan