From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 2BB282D0C79; Tue, 6 Jan 2026 09:30:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767691846; cv=none; b=oIbSUgFZf1Gkv5sR2dRZbGPrQMCD1uZmtjcg7wyA3YH1aEmMCh3zEdtJwgzCcGMM3U2Dd4NZusI2qE0Wk6Ib9xyD5t/3VEZa34e2xDP7Vc7Vw3DdFiRsCfZyPyc08bqAlpw0DYupmbc79s5w/2XUxtvOu6t10Smt9sRyuvR1zf0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767691846; c=relaxed/simple; bh=Q/sXaIxQezX6aDvPY1t5vzmz2Ro0UNgsBgZo+wocFzw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=gNYuAq1rezJzyhTn8QVMBBsukKoemK19ZiPX3V1PdKTVv+e9tu8ak+JTHUPMiX45dogjCuoYi4WcEp4XM+O+AIKfxlcqWYFClEzaUpqCpw0nPkyOyAe4hDmzPqZqUWQKtKDGjVVgcYBke3rMuftuw+NlZig99urWQkb/ejt4C0k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=isLOMPDW; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="isLOMPDW" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 779F1C116C6; Tue, 6 Jan 2026 09:30:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1767691845; bh=Q/sXaIxQezX6aDvPY1t5vzmz2Ro0UNgsBgZo+wocFzw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=isLOMPDWnHNTiI7M5quGfxee9AfWbuFUbchF6dwJmwKhHMBqScMt2ubo3YgmCl3Sy ptxF+/ze2kbKoJS/njy0ponYa6igMZYNNKp9vBaW75oOWEYuM1VWhakfP77FUUTIs3 kRYVRsTyVu53mlj4uXxZsX6p2DQ8kKgmOScBEVmxcF14rB9c8Qoz+p6ykpjd6H+e7N VLhVMYBGRJM6zwNNHGbef39UiyWrAlfoKIYCCKMhmAl5r7VcpkHJQx0+ppJgf2f7pN aI/yLYTpq5iCS+G5fTTWVUa3gz+Wq2GWQCFYag30jhkPeHKNt7G2CSPST9YK5OhKyw ZBcWv6IDperSA== Date: Tue, 6 Jan 2026 10:30:40 +0100 From: Niklas Cassel To: Koichiro Den Cc: jingoohan1@gmail.com, mani@kernel.org, lpieralisi@kernel.org, kwilczynski@kernel.org, robh@kernel.org, bhelgaas@google.com, Frank.Li@nxp.com, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/2] PCI: endpoint: BAR subrange mapping support Message-ID: References: <20260105080214.1254325-1-den@valinux.co.jp> Precedence: bulk X-Mailing-List: linux-kernel@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: On Tue, Jan 06, 2026 at 10:52:54AM +0900, Koichiro Den wrote: > On Mon, Jan 05, 2026 at 05:55:30PM +0100, Niklas Cassel wrote: > > > > You should also verify that the sum of all the sizes in the pci_epf_bar_submap > > array adds up to exactly pci_epf_bar->size. > > I didn't think this was a requirement. I experimented with it just now, and > seems to me that no harm is caused even if the sum of the submap sizes is > less than the BAR size. Could you point me to any description of this > requirement in the databook if available? 3.10.7 Inbound Features "Without address translation, your application address is passed from the TLPs directly through the application interface." Thus, when there is not an explicit translation, the DWC controller passes through a transaction untranslated. Sure, if there is no physical memory or IO registers at the physical address corresponding to the PCI address trying to be accessed, no harm done. But because of the potential security implications, I think it is good to ensure that the whole PCI address range of the BAR has a physical mapping. Kind regards, Niklas