From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-lf1-f48.google.com (mail-lf1-f48.google.com [209.85.167.48]) (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 CBBDAF9E8 for ; Mon, 26 May 2025 18:49:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.48 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748285359; cv=none; b=IATJnravJVaL3VEzams8godgOk0cVYVNhnDfjSZ0urwa6j1sHU2lBfWXG+GuvFEhEqQEwxS4zdszS0wgUaJ5HOsNk/j+Rg5LfhMCP3wk9Z/0P+D+HAt3JUHRQTyQR+FWYxjNrCDvQPy8unPO6nSALOUJ5LRTydMIAUW/Cz/H/yM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748285359; c=relaxed/simple; bh=W6woZj3zpZZ/NpROcizRirvtqvqOuT+F5DQmM/nX7ig=; h=MIME-Version:References:In-Reply-To:From:Date:Message-ID:Subject: To:Cc:Content-Type; b=gGsdhEJqvg11UQvLQ1WBdKxZkM3PPAACv+8qY9qqkseLFesoNo69CbMNIpaqDDlNm5IM+nXqAV8iqoAIO9o73WNzapzSzmnk2uyYYsx+WGz3DEy3T4OeKKeA6kMLivttVSUtYz6qeo+F+RGLBbSsipkeYzUIZdFsEcaQ3mPDlHs= 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=CgjWx38S; arc=none smtp.client-ip=209.85.167.48 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="CgjWx38S" Received: by mail-lf1-f48.google.com with SMTP id 2adb3069b0e04-551fc6d4a76so2937672e87.0 for ; Mon, 26 May 2025 11:49:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1748285354; x=1748890154; darn=vger.kernel.org; h=content-transfer-encoding:cc:to:subject:message-id:date:from :reply-to:in-reply-to:references:mime-version:from:to:cc:subject :date:message-id:reply-to; bh=xKQQZ40MDKPSK/f86/aTfJXDJ4VkASyIAY23NlJ8lls=; b=CgjWx38S+rAHx+KohHDXCYMUDHMf6EHrGelBfY1xs69xkN7QSymZ/57Fpe6hQUAASq JpPx4BsH/Vcn2dhL/EBgC/Pr6IFtlPRmXWZ26A+plTJsJCl7Sw9xSJtCqS0gJYr2unx/ tGUMOqHLg85ZMf/MCRLQeCAz7wMYKkh6a7GJ81xcKSpp05TJ9UzsccOw3AiMIhw0FtAQ ntU+laaxXprKBC2uH36rx/v9IgX6GbwcXHdklWhl4fkRNuj/XdVL7CMt7kTy9es6hFUy k5CEBfNKUdepaXJF4JOWL/LgnC6DjjqsGjP6ROFyahGJ5WaPytNmphPpq1jFAaVDgrFp wN3w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1748285354; x=1748890154; h=content-transfer-encoding:cc:to:subject:message-id:date:from :reply-to:in-reply-to:references:mime-version:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=xKQQZ40MDKPSK/f86/aTfJXDJ4VkASyIAY23NlJ8lls=; b=fxrmRr5YQB/zC1Vn2AeWTt9lKtM7Qi/nzo9JCN4tXmfcP9ht1x1wQxs5vLxy3XdQ1R Xml5oZi4DDZvdRbY8sBShCBrmpo1HKEkMHgPhffJfObb2G68iygcpf4rccjX68SLkfgw xnABaDbqTUAyVQzJmoHSc98HKu6l7GjoyVDid4wpbacnM0DOMKamviqwcAJWtSXjZJgT S35s0u6J5tPxOUMmvFOz1fgvocpBuqHevHKX7DhG+XfhEWdxJX5FNJKdnPcv5XYwlFJs WgqknEBPF6ui5Pyw89pU+k3mCC4GTff4kn1w1G6tU5iibARygk/+1t86SRp05vBX6NYs k9Gw== X-Forwarded-Encrypted: i=1; AJvYcCUVJEX0JYwMaJUWuK2Ird98J19Jb0GvTbC6g4LHHGiYiIsJp7eNj+tNyIqECC8QujWBGu588bC+re0L@vger.kernel.org X-Gm-Message-State: AOJu0Yz7OLjrKIvvigMeenzirZzDrcjYJPtojaS56YDRDCGBmL0EVpb7 j3icoFPOHQBZxEIoCrnz9o2Cvuv1qvd6VNyOXk+D0F1+D9v/u+jFSvn6dE6Ts9LUwagl//vKCSm F91NQPhG8855MzdX/jSx4hihdYNBpfI8= X-Gm-Gg: ASbGncuGlkg7yPbOJ5ujV2EPK7mU+CHWlDSrB2nZfU2YMwzc8G9EtfU6KQCYMSuJmcK aQIH1OeXQuUAqvgBNtyON/BFccyzgyjK6Qx4uiuaIzAN8Ixld0y8AqgyIBJ0v34nYO+nzGicSnQ H2CJkqWBtRw52mSElV8EShwT9UtoluR/A= X-Google-Smtp-Source: AGHT+IEokjisy47mtg9Et8ixdHkIXYMxQD1pDudndPGchPC/fZMl3SdBX1S/SXWAF8nYqEYKdStL7AnDsR1yUfR2xCU= X-Received: by 2002:a05:6512:3c8d:b0:549:5850:f275 with SMTP id 2adb3069b0e04-5521cbaed91mr3042450e87.50.1748285353721; Mon, 26 May 2025 11:49:13 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-m68k@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: In-Reply-To: Reply-To: noloader@gmail.com From: Jeffrey Walton Date: Mon, 26 May 2025 14:48:36 -0400 X-Gm-Features: AX0GCFvmnvi5oSdMSNooWIfR9CtNEuI7DcHM1E4PuVz6UI6wxukB3OuqjYEsBMs Message-ID: Subject: Re: Question on BIGGEST_ALIGNMENT in GCC on NetBSD/m68k To: John Paul Adrian Glaubitz Cc: port-m68k , debian-68k , linux-m68k Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, May 26, 2025 at 2:23=E2=80=AFPM John Paul Adrian Glaubitz wrote: > > On Mon, 2025-05-26 at 14:16 -0400, Jeffrey Walton wrote: > > I don't know about the 64 byte alignment on NetBSD. Maybe it was > > copied/pasted/modified from amd64? amd64 has a BIGGEST_ALIGNMENT of 64 > > due to AVX512. Prior to that, I believe amd64 had a BIGGEST_ALIGNMENT > > of 32 due to AVX. (These were due to the aligned loads, like > > _mm256_load_epi32 (32-byte requirement) or _mm512_load_epi32 (64-byte > > requirement)). > > > > For PowerPC with Altivec, I believe BIGGEST_ALIGNMENT should be 16. > > > > I don't know if __ALTIVEC__ plays a part in BIGGEST_ALIGNMENT. That > > is, should BIGGEST_ALIGNMENT be 4 (for int) or 8 (for doubles) unless > > __ALTIVEC__ is defined; and if __ALTIVEC__ is defined, then > > BIGGEST_ALIGNMENT should be 16. > > The alignment is specified in bits here, not bytes. Hence a BIGGEST_ALIGN= MENT > of 64 means 8 bytes, not 64 bytes. Derp... Maybe the 64-bits/8-bytes is coming from limitations in the linker. See the discussion of __BIGGEST_ALIGNMENT__ at : On some systems, the linker is only able to arrange for variables to be aligned up to a certain maximum alignment. (For some linkers, the maximum supported alignment may be very very small.) If your linker is only able to align variables up to a maximum of 8-byte alignment, then specifying aligned(16) in an __attribute__ still only provides you with 8-byte alignment. Jeff