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 95B963750DC for ; Wed, 20 May 2026 22:18:59 +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=1779315540; cv=none; b=S8MW/Tt48cL5VxiC8LzqmikUPI0KfvPyayTDBMwpfqkV1oI8wUCUW2rg4TMwICTDXpn8P8uEGt3bfSsoYw/US7e1NeLfypIndr8rdmMq8E/Z1dbMhrFc5/7GZ5BwJx9U+aDZ3ktqKm3utwI7jDtU08sp9ha96SOyDkFazlKpnKc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779315540; c=relaxed/simple; bh=oJVYG++22l0ZkD2EbUaq5Dd2xhzGpY7sGStvdPODp5M=; h=Date:From:To:Cc:Message-ID:In-Reply-To:References:Subject: Mime-Version:Content-Type; b=pnEOl94EaJ4SwkBX1wk+mdAHRXO4G9ytLiyd3prG2BudR7BrFAZUR1RYp6NQED0pBkgfZ3ZPQclf/qs6iDcv1JxxOrQsAfctCWQ/Noljpt60OLFx1IlMdOUyoyevJF8mnmVxLoas1bv/6aCTxBYpgXV2LzAVACTdJMbU4ba3q5Y= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Cw5r1y+2; 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="Cw5r1y+2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E4FD11F000E9; Wed, 20 May 2026 22:18:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779315539; bh=JA3E2ofh0uc68UvENOOKPqLGnS5zMobOtk7eMUlt5gU=; h=Date:From:To:Cc:In-Reply-To:References:Subject; b=Cw5r1y+2BEpzwrUqvnlHJAEFHgqpYq4MVY5Gg/3kFCK6vNP/dxO4ZvQHkmoAZaaSs Xt/x6oQJVPeG+a9SsHErwVcxRYgpwCT7pBruY9cDH3PoY1M3yyGinHCxwG7i5Edja3 4DDErrvIgfs8ttSPga22MoxOJTpRfDdCEZqct0QGvspqXYzE5AZvBjEaL8rDxN0AJP TwXxqBF1MQXQbuHadoTvIMBS+JddHto17nNEVM0Ka7Q1liTnRsjFZeag3hi3cT1cPU 4F8E7g6WdWBc7fL1gIsMOgi7eeq1p+Hv/0SuiigaaGdAfstsq78RiPjcObhou0BRyp qofpCQEKw0Kqg== Received: from phl-compute-11.internal (phl-compute-11.internal [10.202.2.51]) by mailfauth.phl.internal (Postfix) with ESMTP id 2DCE4F40084; Wed, 20 May 2026 18:18:58 -0400 (EDT) Received: from phl-frontend-04 ([10.202.2.163]) by phl-compute-11.internal (MEProxy); Wed, 20 May 2026 18:18:58 -0400 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeefhedrtddtgddugeehkeduucetufdoteggodetrf dotffvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfurfetoffkrfgpnffqhgenuceu rghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmnecujf gurhepfffhvfevkfgjfhfugggtgfesthejredttddtjeenucfhrhhomhepfdffrghnucgh ihhllhhirghmshculdhnvhhiughirgdmfdcuoegujhgsfieskhgvrhhnvghlrdhorhhgqe enucggtffrrghtthgvrhhnpedvgeehieekteelueffueehfeejjedvjedvveetfefgffev hedvuedvffevffdvheenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrih hlfhhrohhmpegujhgsfidomhgvshhmthhprghuthhhphgvrhhsohhnrghlihhthidqudej jedvfedtgeehhedqfeeffeelgedtgeejqdgujhgsfieppehkvghrnhgvlhdrohhrghesfh grshhtmhgrihhlrdgtohhmpdhnsggprhgtphhtthhopedugedpmhhouggvpehsmhhtphho uhhtpdhrtghpthhtohepthgvrhhrhidrsghofihmrghnsegrmhgurdgtohhmpdhrtghpth htohepmhgthhgvhhgrsgeskhgvrhhnvghlrdhorhhgpdhrtghpthhtohepuggrvhgvrdhj ihgrnhhgsehinhhtvghlrdgtohhmpdhrtghpthhtohepshhmihhtrgdrkhhorhgrlhgrhh grlhhlihgthhgrnhhnrggsrghsrghpphgrsegrmhgurdgtohhmpdhrtghpthhtoheprhhr ihgthhhtvghrsegrmhgurdgtohhmpdhrtghpthhtohepjhhitgdvfeeskhgvrhhnvghlrd horhhgpdhrtghpthhtohepughjsgifsehkvghrnhgvlhdrohhrghdprhgtphhtthhopehs hhhijhhurdhjohhsvgeshhhurgifvghirdgtohhmpdhrtghpthhtohepshgrthhhhigrnh grrhgrhigrnhgrnhdrkhhuphhpuhhsfigrmhihsehlihhnuhigrdhinhhtvghlrdgtohhm X-ME-Proxy: Feedback-ID: i67ae4b3e:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Wed, 20 May 2026 18:18:57 -0400 (EDT) Date: Wed, 20 May 2026 15:18:56 -0700 From: "Dan Williams (nvidia)" To: "Bowman, Terry" , Mauro Carvalho Chehab , Dave Jiang , Smita Koralahalli , Robert Richter , Jonathan Cameron , "Dan Williams (nvidia)" , Shiju Jose , Sathyanarayanan Kuppuswamy , "linux-cxl@vger.kernel.org" , Ben Cheatham , Lukas Wunner , "PradeepVineshReddy.Kodamati@amd.com" Cc: "linux-kernel@vger.kernel.org" Message-ID: <6a0e33507e961_1717cc100f6@djbw-dev.notmuch> In-Reply-To: <51a77746-5199-44a2-aa2e-d04cdd6084e7@amd.com> References: <51a77746-5199-44a2-aa2e-d04cdd6084e7@amd.com> Subject: Re: RFC: CXL: How to handle trace event ABI break from CXL_HEADERLOG_SIZE fix? Precedence: bulk X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Bowman, Terry wrote: > Hi Mauro and Everyone, > > During development of the CXL protocol series [1], the Sashiko tool > identified an issue in the CXL RAS UCE trace logging for Ports and Endpoints. > Specifically, the CXL RAS UCE header log size is incorrectly defined in > drivers/cxl/cxl.h. > > The UCE header log size is currently defined as 128 u32s (512 bytes), > whereas it should be 16 u32s (64 bytes) per CXL r4.0 8.2.4.17.7. Correcting > this will change the trace format and break the existing ABI contract > with rasdaemon. > > How would you recommend proceeding to resolve this? Split the definitions into one that reads from the register space and once that passes the parsed log to the trace buffer. Something like: u32 hl[CXL_HEADERLOG_TRACE_SIZE_U32]; ...zero-fill that and put a comment about how userspace has already grown a dependency on the buggy size. In other words, keep the userspace compatibility, but fix the iomem overflow.