From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44958) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1egze5-0007q1-6b for qemu-devel@nongnu.org; Wed, 31 Jan 2018 16:10:18 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1egze2-0006vQ-1R for qemu-devel@nongnu.org; Wed, 31 Jan 2018 16:10:17 -0500 Received: from mx1.redhat.com ([209.132.183.28]:48976) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1egze1-0006vF-Qn for qemu-devel@nongnu.org; Wed, 31 Jan 2018 16:10:13 -0500 Date: Wed, 31 Jan 2018 23:10:07 +0200 From: "Michael S. Tsirkin" Message-ID: <20180131230607-mutt-send-email-mst@kernel.org> References: <20180117095421.124787-1-marcel@redhat.com> <20180117095421.124787-2-marcel@redhat.com> <20180131204059.GG21702@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180131204059.GG21702@localhost.localdomain> Subject: Re: [Qemu-devel] [PATCH V8 1/4] mem: add share parameter to memory-backend-ram List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eduardo Habkost Cc: Marcel Apfelbaum , qemu-devel@nongnu.org, cohuck@redhat.com, f4bug@amsat.org, yuval.shaia@oracle.com, borntraeger@de.ibm.com, pbonzini@redhat.com, imammedo@redhat.com On Wed, Jan 31, 2018 at 06:40:59PM -0200, Eduardo Habkost wrote: > On Wed, Jan 17, 2018 at 11:54:18AM +0200, Marcel Apfelbaum wrote: > > Currently only file backed memory backend can > > be created with a "share" flag in order to allow > > sharing guest RAM with other processes in the host. > > > > Add the "share" flag also to RAM Memory Backend > > in order to allow remapping parts of the guest RAM > > to different host virtual addresses. This is needed > > by the RDMA devices in order to remap non-contiguous > > QEMU virtual addresses to a contiguous virtual address range. > > > > Why do we need to make this configurable? Would anything break > if MAP_SHARED was always used if possible? See Documentation/vm/numa_memory_policy.txt for a list of complications. Maybe we should more of an effort to detect and report these issues. > > > Moved the "share" flag to the Host Memory base class, > > modified phys_mem_alloc to include the new parameter > > and a new interface memory_region_init_ram_shared_nomigrate. > > > > There are no functional changes if the new flag is not used. > > > > Signed-off-by: Marcel Apfelbaum > [...] > > -- > Eduardo