From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.zytor.com (terminus.zytor.com [198.137.202.136]) (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 A67DB21CC4A; Fri, 7 Mar 2025 20:10:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.136 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741378242; cv=none; b=K1A9j0EshKLQ444Ixh8DKgK4tyaZv4W/gv27o/h+5mgeWo5mgFxyHLYBECwBGqCcgKQEePCfQLirRjyoWtQFHzBXrUUyOLCVatPCJRP33I2MOTw8j8oyDHRNIo69nAeqrEYCSPYcDNql029GPzqBJsJTv5H9FiPaJS/bpD/A0iI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741378242; c=relaxed/simple; bh=z8uaY0FEvDXDyRuTUQIK7YT1It04TyjrpCzzUcauDks=; h=Date:From:To:CC:Subject:In-Reply-To:References:Message-ID: MIME-Version:Content-Type; b=ERIyRtVGRBShXTUMW6BKbqqehzHe1KYqPk1mBjSQNNUzdsdJxEBLbf7fq1ov6OoXUfD3H1YdMU5YP2EOCBmOm3v+86Rnz0VWihYlxsbfXXSsBVJMgOEwhjQZs3lxnDw30uaPkv8VzTBbzAdJ5wFxIWuteewQv5QFfxTebvQ5W6k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zytor.com; spf=pass smtp.mailfrom=zytor.com; dkim=pass (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b=F3IB7iSH; arc=none smtp.client-ip=198.137.202.136 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zytor.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=zytor.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b="F3IB7iSH" Received: from [IPv6:::1] ([172.56.209.45]) (authenticated bits=0) by mail.zytor.com (8.18.1/8.17.1) with ESMTPSA id 527K79aI409264 (version=TLSv1.3 cipher=TLS_AES_128_GCM_SHA256 bits=128 verify=NO); Fri, 7 Mar 2025 12:07:10 -0800 DKIM-Filter: OpenDKIM Filter v2.11.0 mail.zytor.com 527K79aI409264 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2025021701; t=1741378034; bh=labYh6dS183ez/ccMGDewAeypbKIJUEZ63NUVodYP9Y=; h=Date:From:To:CC:Subject:In-Reply-To:References:From; b=F3IB7iSHYEvDT6RxcaTUE+HY1uOaC4VnUwxKdSJcbsJ/VGwP8hnKFJom4bWfM8OtP AchryuBqXBGLSXDbZ+MsV5uKdxioAoL64EB2Hr82VgdPIiuWZvSICUQIsfj5WGpBgd KriIaJc3fhV0nS1OF/J9ovKepTrInAm9zRKeY8fu9KnjjC1cA61PvXNcMr8KPpE2Si 6ZtEA98YPUR4DMGJMmEfr7slViCtz+0KmVEla3+d3bqWKNRc+yfSLHHLIoMfgw95oG SN+4dF7fYBU8DZVgqTjvri3AONNiYtVQqGQhFLjE5E+swQ4mWdQWMCk66SRGgQ/FHU OiSkGpohg9mHw== Date: Fri, 07 Mar 2025 12:07:02 -0800 From: "H. Peter Anvin" To: David Laight CC: Andrew Cooper , Laurent.pinchart@ideasonboard.com, airlied@gmail.com, akpm@linux-foundation.org, alistair@popple.id.au, andrew+netdev@lunn.ch, andrzej.hajda@intel.com, arend.vanspriel@broadcom.com, awalls@md.metrocast.net, bp@alien8.de, bpf@vger.kernel.org, brcm80211-dev-list.pdl@broadcom.com, brcm80211@lists.linux.dev, dave.hansen@linux.intel.com, davem@davemloft.net, dmitry.torokhov@gmail.com, dri-devel@lists.freedesktop.org, eajames@linux.ibm.com, edumazet@google.com, eleanor15x@gmail.com, gregkh@linuxfoundation.org, hverkuil@xs4all.nl, jernej.skrabec@gmail.com, jirislaby@kernel.org, jk@ozlabs.org, joel@jms.id.au, johannes@sipsolutions.net, jonas@kwiboo.se, jserv@ccns.ncku.edu.tw, kuba@kernel.org, linux-fsi@lists.ozlabs.org, linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, linux-mtd@lists.infradead.org, linux-serial@vger.kernel.org, linux-wireless@vger.kernel.org, linux@rasmusvillemoes.dk, louis.peens@corigine.com, maarten.lankhorst@linux.intel.com, mchehab@kernel.org, mingo@redhat.com, miquel.raynal@bootlin.com, mripard@kernel.org, neil.armstrong@linaro.org, netdev@vger.kernel.org, oss-drivers@corigine.com, pabeni@redhat.com, parthiban.veerasooran@microchip.com, rfoss@kernel.org, richard@nod.at, simona@ffwll.ch, tglx@linutronix.de, tzimmermann@suse.de, vigneshr@ti.com, visitorckw@gmail.com, x86@kernel.org, yury.norov@gmail.com Subject: Re: [PATCH v3 00/16] Introduce and use generic parity16/32/64 helper User-Agent: K-9 Mail for Android In-Reply-To: <20250307195310.58abff8c@pumpkin> References: <4732F6F6-1D41-4E3F-BE24-E54489BC699C@zytor.com> <5A790652-1B22-4D13-AAC5-5D9931E90903@zytor.com> <20250307195310.58abff8c@pumpkin> Message-ID: Precedence: bulk X-Mailing-List: linux-input@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On March 7, 2025 11:53:10 AM PST, David Laight wrote: >On Fri, 07 Mar 2025 11:30:35 -0800 >"H=2E Peter Anvin" wrote: > >> On March 7, 2025 10:49:56 AM PST, Andrew Cooper wrote: >> >> (int)true most definitely is guaranteed to be 1=2E =20 >> > >> >That's not technically correct any more=2E >> > >> >GCC has introduced hardened bools that intentionally have bit patterns >> >other than 0 and 1=2E >> > >> >https://gcc=2Egnu=2Eorg/gcc-14/changes=2Ehtml >> > >> >~Andrew =20 >>=20 >> Bit patterns in memory maybe (not that I can see the Linux kernel using= them) but >> for compiler-generated conversations that's still a given, or the manag= er isn't C >> or anything even remotely like it=2E >>=20 > >The whole idea of 'bool' is pretty much broken by design=2E >The underlying problem is that values other than 'true' and 'false' can >always get into 'bool' variables=2E > >Once that has happened it is all fubar=2E > >Trying to sanitise a value with (say): >int f(bool v) >{ > return (int)v & 1; >} =20 >just doesn't work (see https://www=2Egodbolt=2Eorg/z/MEndP3q9j) > >I really don't see how using (say) 0xaa and 0x55 helps=2E >What happens if the value is wrong? a trap or exception?, good luck recov= ering >from that=2E > > David Did you just discover GIGO?