From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:49416) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RTr8O-0001IV-Qf for qemu-devel@nongnu.org; Fri, 25 Nov 2011 03:27:49 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1RTr8N-0008KS-TE for qemu-devel@nongnu.org; Fri, 25 Nov 2011 03:27:48 -0500 Received: from mx1.redhat.com ([209.132.183.28]:46132) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RTr8N-0008KO-Jg for qemu-devel@nongnu.org; Fri, 25 Nov 2011 03:27:47 -0500 Message-ID: <4ECF517F.5050000@redhat.com> Date: Fri, 25 Nov 2011 09:27:43 +0100 From: Paolo Bonzini MIME-Version: 1.0 References: <1322067087-16884-1-git-send-email-pbonzini@redhat.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [RFC PATCH 0/3] block: add support for 4k logical blocks List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Mark Wu Cc: qemu-devel@nongnu.org On 11/25/2011 08:26 AM, Mark Wu wrote: > 1. This patch aims to add 4k logical support for qemu running on a host > with 4k logical block size, right? No, it adds support for 512b logical block sizes running on a host with 4k logical block size and cache=none. This is suboptimal as it requires bounce buffers, but it can happen with migration and until libvirt provides a knob for the guest's logical block size. > For guest, we can use > logical_block_size=4096 to achieve that even on a host with the > logical_block_size of 512. Am I right? Yes. > 2. Can we just call bdrv_get_alignment in bdrv_open_common once and use > the stored buffer_alignment for future usage instead of always > calling bdrv_get_alignment in qemu_blockalign/qiov_is_aligned. What's > the benefit of the dynamic way? Yes, I think it's possible. Paolo