From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: [Qemu-devel] [RFC v2 00/20] Memory API Date: Mon, 27 Jun 2011 10:37:42 -0500 Message-ID: <4E08A3C6.5080409@codemonkey.ws> References: <1309180927-19003-1-git-send-email-avi@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org To: Avi Kivity Return-path: Received: from mail-yw0-f46.google.com ([209.85.213.46]:49585 "EHLO mail-yw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751144Ab1F0Php (ORCPT ); Mon, 27 Jun 2011 11:37:45 -0400 Received: by ywe9 with SMTP id 9so1880501ywe.19 for ; Mon, 27 Jun 2011 08:37:44 -0700 (PDT) In-Reply-To: <1309180927-19003-1-git-send-email-avi@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 06/27/2011 08:21 AM, Avi Kivity wrote: > As expected, this is taking longer than expected, so I'm releasing something > less complete than I'd have liked. Not even all of the PC machine is > converted, but the difficult parts are (cirrus). It appears to work well. > > The major change compared to v1 is the introduction of > memory_region_init_alias(), which defines a memory region in terms of another. > With the current API, the ability to alias is provided by address arithmetic > on ram_addr_t: > > ram_addr = qemu_ram_alloc(...); > cpu_register_physical_memory(..., ram_addr, size, ...); > /* alias: */ > cpu_register_physical_memory(..., ram_addr + offset, another_size, ...); > > With the new API, you have to create an alias: > > memory_region_init_ram(&mem, ...); > memory_region_register_subregion(...,&mem); > /* alias: */ > memory_region_init_alias(&alias, ...,&mem, offset, another_size); > memory_region_register_subregion(...,&alias); What's the rationale for explicit aliasing verses registering the same region to two different address spaces? Regards, Anthony Liguori