From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qv1-f42.google.com (mail-qv1-f42.google.com [209.85.219.42]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 01E123E92A1 for ; Tue, 14 Apr 2026 15:11:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.219.42 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776179489; cv=none; b=TNGcQ14SWytcyIFDQ0EeFjGIUrHrbzYCtzGh7jKSwoeJHnpzKyzUPAzH+ncdLXpZea+VRFTITIqI7GMn+BrYBux7r8JxjtRfajzxuLXLahiBqw5WwKl4uTuiBjT4WEBzeeSYKUSRpw7LrNP3/BcsyO09YD2xX/KVLR2Z1fADLck= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776179489; c=relaxed/simple; bh=wtmKouu1J13QOKEWpC/Rhgp+PUitDlJyO7jIdqkEIVo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=gsTfZhP5UNsnsSLpRj6TpzYZmvy5ZE5lyn5Y5w4HFZdFGxfM591T9NU0kFJ+FYjn99J4nlOG3Ts1PX5AfNBHNA2HOVpDzUgMa7GQF017CvO7NltKBMTV2mwwtnAUxSmsSck2dJ6xVqviwI3LCTeU2B76MvFZtnzSSEfmcMrAGAw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ziepe.ca; spf=pass smtp.mailfrom=ziepe.ca; dkim=pass (2048-bit key) header.d=ziepe.ca header.i=@ziepe.ca header.b=LOR05mK+; arc=none smtp.client-ip=209.85.219.42 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ziepe.ca Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ziepe.ca Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ziepe.ca header.i=@ziepe.ca header.b="LOR05mK+" Received: by mail-qv1-f42.google.com with SMTP id 6a1803df08f44-8acb550db18so19085076d6.3 for ; Tue, 14 Apr 2026 08:11:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; t=1776179487; x=1776784287; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=KYWxsN8NcBk0hkmTwyrJ9dFetqgCC/fPQOeOuZaqCQI=; b=LOR05mK+HpHUZy18w4Dk7mDIMTVt2CqGJv6K1mBA55KO1uywBz8h8IBKBzhn4aHAO9 vH0NS+fuTcuiKi0VoxchkLiUtLN6rj7dqxajvrCuQyW0IdXx5NElXiYa4YWn5DDd/BtR WFgWMEErubR+eerVtOWit7waU1BfplQlQbeI0ukBBX1Hfp8klPZxXlCJOs/B4824tYD6 vOMiryVGnE37XdbdYE5g3wxBwhLNymPEJbmA6ALYM/d6B+I5HUMss6Fc9WF0N1a3VH7u OcXMJI2BDU4/8aMgg7lU7yp0PYDLaJwX/fP8wrU46jXXqbpXimJy41RSnyg/4SlBtXPv 9LPg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1776179487; x=1776784287; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=KYWxsN8NcBk0hkmTwyrJ9dFetqgCC/fPQOeOuZaqCQI=; b=UVix86njmC4wUvhpLHdaU3l0aR+TS/LNlGCltZHaA280Mqy6gzC4mCO3l9dvNA1XTb DScHO/jyelPXawbUIcImmeZ1iSE55i9EjJ7vA5PdI3I+yRhRsvsbBySAo7aiuXors05J jjcDrIJZK7aNbFqf1r835d6ISncxSplGiiy7cK9v9TjNulCkdLgmZf3ziHi/Xa3vS77L ovTx1yxKR/BfJ6OF036RPFRW0UiMSkfK2ue2aWwYtPdfKPRe9fmgNSITQKZnvqHuX11u SfeoZE4mpriR/uhy/eSjQnQoj5KA/O9TlnRuOExpiJOM1onB2UAJDutVAPmOBaQ1Ivmn pV/Q== X-Forwarded-Encrypted: i=1; AFNElJ+LHjF4Ucl3Rzypau/O2esFGX06fgfRpPkApeWaalgNXkFkoagfcnOmdTpZYPebX8BfA0jqTYg=@vger.kernel.org X-Gm-Message-State: AOJu0YwvwDuARCUfex6yC/p/zLhsQhXRo2zV0GgktqhDiDOhus1JX4O7 Kj7RUsJrVfjK07304WyIXERdnBliEd5tz9N/ukkjh5EDXKC4OdUDqNTwAoO099MA/Yg= X-Gm-Gg: AeBDiev+x6Lla2z14Bd8JylJbz7KUrafdpMsxdt4e5K2e0kIwDwbN4RWybmzrMnETWe LnW0yvJPdTmcbzHqD4DvRhcdAcqPdRTuQA9dWg9CkigcDtHc4ZS9WuD58VWkIBT37Z/2LfDwIWw 9GULXylqnEC1LnjW5MNykONbInrnV9jWzWvDhcd8VRu6HQ7In2XwfANK+DAUYEBfkDCN/AedoFU 2in3crDOVoAt8oFsAah8Bf8qJnLhXtmD7LRaKFsRcQh9DBtoXhy92/aeRdSO6Np0BsRVhkQRrd0 ta3pYJWJSRRK45D0h3gTgQTioQZ3L/NPWXgkIVopejDndKauc8lUele84sQ4paIhOy9RbqqRtqA 8ZF6bht+ZaLBE5Tds9MyKzgLGJoXd3CyWYIODvX65x336UBM6lAVMgJskWkMSaLpwKMwpPrF+MU 8zZ8RBj11pxnHBs0fJauNKa27FDQCuFUz9Gu36J7eapvxaWz/BlHsBLLH1AsoT0TPPNK3PKpTeQ bcLFg== X-Received: by 2002:a05:6214:4a01:b0:89c:8709:d238 with SMTP id 6a1803df08f44-8ac862b51e2mr284214856d6.40.1776179487026; Tue, 14 Apr 2026 08:11:27 -0700 (PDT) Received: from ziepe.ca (crbknf0213w-47-54-130-67.pppoe-dynamic.high-speed.nl.bellaliant.net. [47.54.130.67]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-8ac849e35afsm159006516d6.3.2026.04.14.08.11.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 Apr 2026 08:11:26 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1wCfQD-0000000BNfx-2aVf; Tue, 14 Apr 2026 12:11:25 -0300 Date: Tue, 14 Apr 2026 12:11:25 -0300 From: Jason Gunthorpe To: fengchengwen Cc: Leon Romanovsky , Bjorn Helgaas , linux-rdma@vger.kernel.org, linux-pci@vger.kernel.org, netdev@vger.kernel.org, dri-devel@lists.freedesktop.org, Keith Busch , Yochai Cohen , Yishai Hadas , Zhiping Zhang Subject: Re: [RFC] Proposal: Add sysfs interface for PCIe TPH Steering Tag retrieval and configuration Message-ID: <20260414151125.GF2577880@ziepe.ca> References: <6ea4c4c2-774e-aa76-3665-918e2a24cc84@huawei.com> <20260413100152.GG21470@unreal> <20260413191930.GP21470@unreal> <20260414085723.GR21470@unreal> <84bf119e-fa8c-4c97-9197-3377b7e2b250@huawei.com> <20260414103547.GA361495@unreal> <11eaea26-ec10-264a-db1e-951f6b46078d@huawei.com> Precedence: bulk X-Mailing-List: netdev@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: <11eaea26-ec10-264a-db1e-951f6b46078d@huawei.com> On Tue, Apr 14, 2026 at 10:46:00PM +0800, fengchengwen wrote: > We have a real platform requirement: > > * 1. Devices in TPH Device-Specific Mode with no standard ST table > * 2. Steering Tags must be obtained from ACPI _DSM (kernel-only) > * 3. Devices are fully managed by userspace drivers (VFIO/UIO) > * 4. Userspace must program STs into vendor-specific registers No, this is nonsenscial too. If you want to control the steering tags for MMIO BAR memory exposed by VFIO then the DMABUF mechanism Keith & co has been working on is the correct approach. If the VFIO user needs to control steering tags for the device it is directly controling then it must do that through VFIO ioctls. Nobody messes around with other devices under the covers of the operating kernel driver. Stop proposing that. Jason