From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 58EBC1CD3F for ; Wed, 11 Dec 2024 14:25:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733927124; cv=none; b=L1JfBW2VaXmjakCMxtFEWGQcChdATkRjdWcybSsmWTzA6rTgZIWuEb962c2iAL8UHNVowpP4mtrNOc49Tto5HLo1SeNpe2BknDnH08qHCzXWfzOK7i5QJkLyfV/1CQv1Uz9HrcjepULrK3+7FKkttwPDnzPQPGv/KuaznyoYylI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733927124; c=relaxed/simple; bh=GAvbBO+3gCE4FFhULFUzZtgq1FYbyAHcvmDxLqDyQhQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=hzpy/2fhlsTRrz9uC8W+niTw9l6fnltxNUpkgVCHXitmT/0YDwJe2RQg2ABJjQrnsHVuxLw0ciL6/oRTTHuruGc9eVJMkAghilt//C1P2Iqgu3VQBgbaEbozG2JQ+kYdzMsbrgb0Ke4UbeDIWfv8BVgXXgOuYrbC23N1i84ZKlw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=oZ3V66Se; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=d7+F9tU8; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="oZ3V66Se"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="d7+F9tU8" Date: Wed, 11 Dec 2024 15:25:17 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1733927119; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=JniKxZaKIckwpZT/I3NSeEVGJX/9DihSJgU5m9ylrJY=; b=oZ3V66Sew7gClffQOrHqY78VWXJUbUzqFXHLdb6mAJUHtN2lM53BRX0HxOUm21QQDlSmIH r2Ka4+RbT0M60LM3aE+tOiVwbNWJptwi+foi/VMCODdUgV60nNKhYtMPiBiCZJ3+Aadwuo n01zz9i0K1crpJHShTz83I6JmdMyw76zmLNbbqUPBDHmCbydd0cDAwFVRnHT9NOxM7++77 4oZN6WBmzSPwKY2UPo38UjvNSx5un1kF5593+Ab9mC3RoZghFEXjR8kahVmgPkknbVNrBA kmZuBQiND+pNNb/1mE+4GpqyYThyVarfjAaNZ4VxZKr30fb19DyElD/6DjObXQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1733927119; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=JniKxZaKIckwpZT/I3NSeEVGJX/9DihSJgU5m9ylrJY=; b=d7+F9tU81J6PP0W/cr25Ib9q5pTZelDPbjs7enEICI6UojHUyU8/5vvl8k9YB0rsU4bX1d LahZ3EQ1IsluJFAA== From: Sebastian Andrzej Siewior To: Arnd Bergmann Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Arnd Bergmann , linux-mm@kvack.org, linux-rt-devel@lists.linux.dev, Ard Biesheuvel , Clark Williams , Jason Baron , Josh Poimboeuf , Linus Walleij , Mark Rutland , Matthew Wilcox , Peter Zijlstra , Russell King , Steven Rostedt Subject: Re: [PATCH 3/4] ARM: drop CONFIG_HIGHPTE support Message-ID: <20241211142517.fhnOz46I@linutronix.de> References: <20241210160556.2341497-1-arnd@kernel.org> <20241210160556.2341497-4-arnd@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20241210160556.2341497-4-arnd@kernel.org> On 2024-12-10 17:05:55 [+0100], Arnd Bergmann wrote: > From: Arnd Bergmann > > CONFIG_HIGHPTE was added in linux-2.6.32, a few years before 64-bit > support. At the time it made sense, as the CONFIG_ARM_LPAE option allowed > systems with 16GB of memory that made lowmem a particularly scarce > resource, and the HIGHPTE implementation gave feature parity with 32-bit > x86 and frv machines. > > Since Arm is the last architecture remaining that uses this, and almost > no 32-bit machines support more than 4GB of RAM, the cost of continuing > to maintain HIGHPTE seems unjustified, so remove it here to allow > simplifying the generic page table handling. > > Link: https://lore.kernel.org/lkml/20241204103042.1904639-8-arnd@kernel.org/T/#u > Signed-off-by: Arnd Bergmann > --- > I sent a patch to drop HIGHPTE support on x86 today, see > https://lore.kernel.org/lkml/20241210144945.2325330-9-arnd@kernel.org/T/#u > > If that one gets merged, we can merge this one instead of the one > that makes HIGHPTE depend on !PREEMPT_RT, but if we decide against > the x86 change, then we probably don't want this one either. Based on what I have written in 20241211140402.yf7gMExr@linutronix.de it makes sense. Acked-by: Sebastian Andrzej Siewior Sebastian