From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Moyer Subject: Re: [PATCH v8 6/7] sd: Implement support for ZBC devices Date: Wed, 19 Oct 2016 09:23:04 -0400 Message-ID: References: <1476772835-18541-1-git-send-email-damien.lemoal@wdc.com> <1476772835-18541-7-git-send-email-damien.lemoal@wdc.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: Received: from mx1.redhat.com ([209.132.183.28]:59960 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S942868AbcJSOlt (ORCPT ); Wed, 19 Oct 2016 10:41:49 -0400 In-Reply-To: (Shaun Tancheff's message of "Tue, 18 Oct 2016 13:22:11 -0500") Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Shaun Tancheff Cc: Damien Le Moal , Jens Axboe , linux-block@vger.kernel.org, linux-scsi@vger.kernel.org, Christoph Hellwig , "Martin K . Petersen" , Hannes Reinecke , Shaun Tancheff , Damien Le Moal Shaun Tancheff writes: > On Tue, Oct 18, 2016 at 11:58 AM, Jeff Moyer wrote: >> Damien Le Moal writes: >> >>> + if (!is_power_of_2(zone_blocks)) { >>> + if (sdkp->first_scan) >>> + sd_printk(KERN_NOTICE, sdkp, >>> + "Devices with non power of 2 zone " >>> + "size are not supported\n"); >>> + return -ENODEV; >>> + } >> >> Are power of 2 zone sizes required by the standard? I see why you've >> done this, but I wonder if we're artificially limiting the >> implementation, and whether there will be valid devices on the market >> that simply won't work with Linux because of this. > > The standard does not require power of 2 zones. > That said, I am not aware of any current (or planned) devices other > than a power of 2. > Common zone sizes I am aware of: 256MiB, 128MiB and 1GiB. > > Also note that we are excluding the runt zone from the power of 2 expectation. > > So conforming devices should (excluding a runt zone): > - Have zones of the same size. > - Choose a zone size that is a power of 2. OK, thanks for following up. As long as the drive vendors are on board, I guess we're okay. :) -Jeff