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 X-Spam-Level: X-Spam-Status: No, score=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 60DC5C432C0 for ; Fri, 29 Nov 2019 09:55:11 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 28C992176D for ; Fri, 29 Nov 2019 09:55:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Y1PK7SC5" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 28C992176D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:56522 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iaczV-0006hO-Bg for qemu-devel@archiver.kernel.org; Fri, 29 Nov 2019 04:55:10 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:35404) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iacl4-0005i0-NR for qemu-devel@nongnu.org; Fri, 29 Nov 2019 04:40:17 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iacks-00060N-Oz for qemu-devel@nongnu.org; Fri, 29 Nov 2019 04:40:08 -0500 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:37554 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iackr-0005nP-KN for qemu-devel@nongnu.org; Fri, 29 Nov 2019 04:40:02 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1575020399; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=cEi63xphGA0hDHE99c1lbTzYSPufT+CNiHr6UJwxBtM=; b=Y1PK7SC5WtZJwldtd8x3bz8xKDRGP+HXfHmzDfmyzhTAlq/BD6aW7zQB6XG0lwuQMXAb0e mKADcOKi5puuYY8LIyJfTYCj3a9eBqbW+XR2O97JK69NBQamFqtyLk/QQdtec1cZ/Nvzz7 Wt2Mnh5+tAb0bXtvQ/GymG94QIg/6BI= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-327-Yrfb_ilDNeyUFGTe4a4Gtg-1; Fri, 29 Nov 2019 04:39:56 -0500 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 003D1107ACC4; Fri, 29 Nov 2019 09:39:55 +0000 (UTC) Received: from redhat.com (ovpn-112-31.ams2.redhat.com [10.36.112.31]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B09AF60BF1; Fri, 29 Nov 2019 09:39:44 +0000 (UTC) Date: Fri, 29 Nov 2019 09:39:41 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Paolo Bonzini Subject: Re: [PATCH 0/2] RFC: add -mem-shared option Message-ID: <20191129093941.GD2260471@redhat.com> References: <20191128141518.628245-1-marcandre.lureau@redhat.com> <20191129070253.5hwksjrapomk434x@sirius.home.kraxel.org> <20191129092713.GA2260471@redhat.com> <6b441014-1852-3257-2bc5-897cc51d08dc@redhat.com> MIME-Version: 1.0 In-Reply-To: <6b441014-1852-3257-2bc5-897cc51d08dc@redhat.com> User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-MC-Unique: Yrfb_ilDNeyUFGTe4a4Gtg-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.120 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Eduardo Habkost , qemu-devel , Gerd Hoffmann , Stefan Hajnoczi , =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, Nov 29, 2019 at 10:33:39AM +0100, Paolo Bonzini wrote: > On 29/11/19 10:27, Daniel P. Berrang=C3=A9 wrote: > >> Yes, with a fallback path currently using a temporary file under /tmp > >> (we may want to use shm_open() instead, or a different location such > >> as XDG_RUNTIME_DIR? - and use O_TMPFILE) > > We can't assume either /tmp or XDG_RUNTIME_DIR is on tmpfs as that is n= o > > where near standard across all OS distros, and even if on tmpfs these > > dirs can be size limited to a significant subset of available RAM. IOW > > we can't safely use them unless explicitly told to. >=20 > Agreed, mkstemp+shm_open seems better. Perhaps this could be done in > hostmem-memfd.c though, basically as a fallback option? In principle > one could even use getmntent to search for a hugetlbfs mount. With mkstemp you still need to pick a location, and I don't think it is clear there is a reliable choice that will always work. Regards, Daniel --=20 |: https://berrange.com -o- https://www.flickr.com/photos/dberrange= :| |: https://libvirt.org -o- https://fstop138.berrange.com= :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange= :|