From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 08CFDCF6493 for ; Sat, 28 Sep 2024 16:08:43 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [127.0.0.1]) by lists.ozlabs.org (Postfix) with ESMTP id 4XGC1k0W64z2xs0; Sun, 29 Sep 2024 02:08:42 +1000 (AEST) Authentication-Results: lists.ozlabs.org; arc=none smtp.remote-ip=170.10.129.124 ARC-Seal: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1727539721; cv=none; b=c7+VgMdBxqHj20OnemuhT/saUC9i9B5w1GptFtDp1PCfNVhQOpBa21+yqRopHXJByVjdFftTyD8Ypquaf/8AhJPgWDAuCoGR/tyAUcUP1xE5aoeGFYXgTHs5vv8cAxwOZqPeXwIQU+qFO90p5wfJrZQcWdWnnXtoDA0HyoE7AxFhVdcC7pgLUtxAkmjytcid5wEmgsmVySSMgHHjWMNUaFqqu+n4DrcfSNm/nQLy+8t1r4rCDAx2gblKOtYA9bok2GS4PUfA5Qr4ZIGMD+bkw5bBA+mm1KE4kNkDjksvV6M0eOhv2XCrb9HSsBoIhod8pEKFDiP97WxXd02Wl4HfCA== ARC-Message-Signature: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1727539721; c=relaxed/relaxed; bh=BVhyGdzPo5lwXgUtI6R/o6Hb5c4Wd+LA4o4nC6SZqH4=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version:Content-Type; b=eGuIZUvRyi+6pNh5FLWUth0scZ1ft0V8FJG/wCo/WlfakpUAZj6+NPbRBj7eR2783RBCugLQu2bQU1MmZ7QW/Es1xySwBCSfyZuICAQY1B11NA7xTdtvw7HOwdcmCWqbcBx5Y61KKSJC1Svb3dxrQBgzPSNSDRX/z68l9QXjOfA7wAnDE+JFw4VKDeMp/y/gqFUbjBtwFLjEPQdEtN+JmQ85BjS+ovmIVLivJLLL6M2JH6qD+hTmXkb1SXdaBVAuz7S+7uKIpMFpXxrz2FKKb7tPlhbqUSxt/ZOjXnN5YHxZbMTkK4ca79eDmJd1ksTwqBoD7hvdIP7yx8ym8OybBw== ARC-Authentication-Results: i=1; lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=redhat.com; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=UeNf2Bbo; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=UeNf2Bbo; dkim-atps=neutral; spf=pass (client-ip=170.10.129.124; helo=us-smtp-delivery-124.mimecast.com; envelope-from=fweimer@redhat.com; receiver=lists.ozlabs.org) smtp.mailfrom=redhat.com Authentication-Results: lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: lists.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=UeNf2Bbo; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=UeNf2Bbo; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=redhat.com (client-ip=170.10.129.124; helo=us-smtp-delivery-124.mimecast.com; envelope-from=fweimer@redhat.com; receiver=lists.ozlabs.org) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4XGC1h1yv2z2xnc for ; Sun, 29 Sep 2024 02:08:37 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1727539712; 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; bh=BVhyGdzPo5lwXgUtI6R/o6Hb5c4Wd+LA4o4nC6SZqH4=; b=UeNf2Bbo+/Z/bOvtchQkM9nTZjMUlgpwANSCOLu5C+Hmq3x30PQpdPOLloDs0LnAd/V/bY jPvvDuCi/GreuC8gp4pOoarIH44GKwkGanC2Xlov42nQZ5qpiwxBQbn8fbAbUfvzYKaLod O5duKzjFUB28nPgTUA6VNvVKlZFEmFc= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1727539712; 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; bh=BVhyGdzPo5lwXgUtI6R/o6Hb5c4Wd+LA4o4nC6SZqH4=; b=UeNf2Bbo+/Z/bOvtchQkM9nTZjMUlgpwANSCOLu5C+Hmq3x30PQpdPOLloDs0LnAd/V/bY jPvvDuCi/GreuC8gp4pOoarIH44GKwkGanC2Xlov42nQZ5qpiwxBQbn8fbAbUfvzYKaLod O5duKzjFUB28nPgTUA6VNvVKlZFEmFc= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-245-NdxP2ncqPT6o1klT9XOD5g-1; Sat, 28 Sep 2024 12:08:28 -0400 X-MC-Unique: NdxP2ncqPT6o1klT9XOD5g-1 Received: from mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (unknown [10.30.177.15]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 0575619780C8; Sat, 28 Sep 2024 16:08:28 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.45.224.151]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 89B4A1979060; Sat, 28 Sep 2024 16:08:26 +0000 (UTC) From: Florian Weimer To: linuxppc-dev@lists.ozlabs.org Cc: Peter Bergner Subject: Are 256K page sizes really a thing (on ppc64le in particular)? Date: Sat, 28 Sep 2024 18:08:23 +0200 Message-ID: <87cyknzrpk.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Post: List-Subscribe: , , List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain I'm working on adding a header to glibc, so that programmers can easily determine the range of possible page sizes for a particular target, for things like pointer tagging and mapped file alignment requirements. I'm not familiar from the Kconfig system, but as far as I can tell, this ensures that 256 KiB pages are only available on 44x machines: arch/powerpc/Kconfig-config PPC_256K_PAGES arch/powerpc/Kconfig- bool "256k page size (Requires non-standard binutils settings)" arch/powerpc/Kconfig- depends on 44x && !PPC_47x arch/powerpc/Kconfig: select HAVE_PAGE_SIZE_256KB And none of the 44x configurations set 64BIT, so it's all 32-bit. Would it still make sense to recommend 256 KiB file alignment to programmers on 32-bit PowerPC, or should pretend that the maximum page size is 64 KiB? Thanks, Florian