From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f47.google.com (mail-wm1-f47.google.com [209.85.128.47]) (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 540361A4F3C; Fri, 7 Mar 2025 19:53:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.47 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741377197; cv=none; b=DWrLWxwZQlqP0YMemrRUK85voiMjnbgac68d5dA6x57YT4QMiAKIU40gYuyHLqaUBpdKQiImKVr/SrA6XubUdzIbHBHYs4rgHPlECDwiERAvm6wBH1GrCrQ4fAsI4K1vq1Wi0lVSuX98AjTCdMKEH4EiJ1RA43AwiDOu5OTQnoI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741377197; c=relaxed/simple; bh=LNHS/O5qk8V3R4mU1dNCTKTGoEiRwLqi9UP8XhBs1YI=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=N8pErDizUMC8DDxjx4Mvsk30Onu2iDjel45rHtk+6pc6bRX2miV+LlZwuDTt1NKiQlOm6zXzRd1SxKN2jgNWmZvaXSFW4QZEU1A96K1cpudV9C10PX0sceaP4PCucNfg8eAcwYLDAYG62ByyLSg6L4uEqz7lRwSzGQRa2IxEgG0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=kb5jl3f7; arc=none smtp.client-ip=209.85.128.47 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="kb5jl3f7" Received: by mail-wm1-f47.google.com with SMTP id 5b1f17b1804b1-438a39e659cso13250065e9.2; Fri, 07 Mar 2025 11:53:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1741377194; x=1741981994; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:from:to:cc:subject:date :message-id:reply-to; bh=OFjCWoFVVseHqDKPyVju+l4iTZxEMM/BbzUS5g6rWQg=; b=kb5jl3f7XFMcjOTPKOzvk+iJs5Pb5+mKTp9Jyt2MyRfgGGfAPnW81BqWlx+n29EnB5 HC/oHdZB9Keqf+rN1ACTB1pNTf37gWpfcE/7uaGzxifp5+50dXAxgk4ixrKutgx4o6Nz CP1wzm5+ZgkxGG5NGzUuW23jgf45WmG4AYyzPgvcJ1jf5cg1pTiwMk1LriCxGqXwKd6e PeExadqaVN57vYQdN21528j1nA+oa8FG5olSGGd+3GKsBR2Szwp+3eYZwJLbTdMtQqzR oTFtz/32/jj/VcQdaqr1S9xRaO3Kwj1SxoEDR5MmtpYBn49CMyz6l3c/xa30XNxceYbP ndvg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1741377194; x=1741981994; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=OFjCWoFVVseHqDKPyVju+l4iTZxEMM/BbzUS5g6rWQg=; b=e4N/cFXpuy7TUqN1tFk+sYWwE9tza69iiCxt+FTi/ZuzVoU73cGRpolPwDdtRFn3P4 YzSpLbxPjSKN0wgjyEcBruRpo42996EoXZKq5+t57XgRZ4zO5xSXY1VqDvjMjCTWCNvd Lt4xQQ/PAipcCs2vfb5WJeyzbPJkT9mb6lYrVpy8N9Fvwjx3NH8F2BzoEWdXnWYEEnkq nz9uGSC008nR3FjmMtWT/7kzuKKuZO+9wM//Zf/togdwxe6NU70uusFY3cuTgvuMltkj W4kLC9oC4p14c+fwfW7tpc1cIsfzvJeUo9q7w0CoogIWANX5dQ6TnuwVs+ZTps0gO60F WBRw== X-Forwarded-Encrypted: i=1; AJvYcCV1KNS1Wfx5vnaVLLWgCA5a9GYPk1hEDwm6r6pqFHTQk+hMC8ziw+HrDCdRC7adBhmrdj0=@vger.kernel.org, AJvYcCV486pIEFjoKrrvnbJk6kZqOWGY2TEtfIhMlE04LoQEPOJiC8WKapWXCpmT2B8R3XDVzrWjg9wz1eHyHJHX@vger.kernel.org, AJvYcCVSWviZas7P2ndmQzi4ig4Xqul7atnTVgIAmK0EhfsXYIzh1pHLIxOqOk3ErKToQtRJ+xJPsfdOz1RjMIzAQd8=@vger.kernel.org, AJvYcCWb9966QWA7Mt1ol+84XzJyiy3IZ3ApsVkBQ0+gSHLHdFJ3HxZR2Sf9izxFnxyL65YEIhhmzxTlammMbpE=@vger.kernel.org, AJvYcCXa1zqEsfBnK6+tMru9h1ls8GgLtYzi/dBfnGJZk2JNVG/d8PKmiRw/2tHsGVELAfSVU4cEq0r6vh7i+cE=@vger.kernel.org, AJvYcCXcoIxzCONdTPmph2yADDUx/oIGOd5+BMeb+3983oxJWCOjmyRMcikQbPlujiag21i8WGQ7dzBH@vger.kernel.org, AJvYcCXeX1aGXcQWLcuQ/j34AlF3VAK+1yFECddR0b1Xq/Iw7clPhVxlA/i/sfT/pNS3s43K86SFPaIQ2azYr9+q@vger.kernel.org X-Gm-Message-State: AOJu0YzCeDQ3XOefdeNwWOyWlt8WAGG2k0lZeOZ5qhkdsj9HSBm8hrpq tcON1DYFTyaqwrYn2iAJG5XfI+0Kz5PVgc5slaNvsHu2iqK8ABQE X-Gm-Gg: ASbGncvB0+y8GWDg2jdy2TpXj+sxAopY3CYUSjtsMOa8SgqE/RoghUL+spc/DbkcBoO HfUM5kPWiaQJmRfM+qP/X/rWYoHeThQ62RSOkHeGDjbkGNI7YY5jnHslYZ0iph3Kq6eS9R93lOf rfkDzc8+lIX82i7Qy3E6mE8k5EDmQEOJqLtLqKIQ00I3bUy7B+mZ0+JYWz725/FxUa9P+CbcWib 22QIoGKC8lewgbUMxLWFPcv+6rCpf+4fYpQmqQDj1b+tlEZlVHL9WnQklApDuY7KRcz7A4tA7H6 Kkwrq1d4uhktFCWpVG81XjFTNFhyGfYCm6FwhhXxTY+ZzB4gnAeNCMHi/kms8R426sRB2hRQ/Ut 05RaJTuw= X-Google-Smtp-Source: AGHT+IFtUYsYiNnYKhfvrcaN1ioOhGevW7gRyAbgDR19AZMXszweQZgGUKeQX4mOm4dqyM9BgE29Gg== X-Received: by 2002:a05:6000:18ab:b0:391:122c:8aa with SMTP id ffacd0b85a97d-39132d96079mr3226538f8f.30.1741377194381; Fri, 07 Mar 2025 11:53:14 -0800 (PST) Received: from pumpkin (82-69-66-36.dsl.in-addr.zen.co.uk. [82.69.66.36]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3912c01d2cdsm6394936f8f.57.2025.03.07.11.53.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 07 Mar 2025 11:53:13 -0800 (PST) Date: Fri, 7 Mar 2025 19:53:10 +0000 From: David Laight To: "H. Peter Anvin" 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 Message-ID: <20250307195310.58abff8c@pumpkin> In-Reply-To: <5A790652-1B22-4D13-AAC5-5D9931E90903@zytor.com> References: <4732F6F6-1D41-4E3F-BE24-E54489BC699C@zytor.com> <5A790652-1B22-4D13-AAC5-5D9931E90903@zytor.com> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: linux-serial@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Fri, 07 Mar 2025 11:30:35 -0800 "H. Peter Anvin" wrote: > On March 7, 2025 10:49:56 AM PST, Andrew Cooper wrote: > >> (int)true most definitely is guaranteed to be 1. > > > >That's not technically correct any more. > > > >GCC has introduced hardened bools that intentionally have bit patterns > >other than 0 and 1. > > > >https://gcc.gnu.org/gcc-14/changes.html > > > >~Andrew > > 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 manager isn't C > or anything even remotely like it. > The whole idea of 'bool' is pretty much broken by design. The underlying problem is that values other than 'true' and 'false' can always get into 'bool' variables. Once that has happened it is all fubar. Trying to sanitise a value with (say): int f(bool v) { return (int)v & 1; } just doesn't work (see https://www.godbolt.org/z/MEndP3q9j) I really don't see how using (say) 0xaa and 0x55 helps. What happens if the value is wrong? a trap or exception?, good luck recovering from that. David