From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: [PATCH] libata: increase LBA48 max sectors to 65535 Date: Wed, 15 Feb 2006 15:21:29 -0500 Message-ID: <43F38D49.4080601@pobox.com> References: <1139754779159-git-send-email-htejun@gmail.com> <43EF8E61.5040409@pobox.com> <43EFD73D.4070207@gmail.com> <43F011DF.6020203@pobox.com> <20060215072449.GA31691@htj.dyndns.org> <20060215130725.GP4203@suse.de> <43F342E6.9060909@gmail.com> <20060215151200.GW4203@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail.dvmed.net ([216.237.124.58]:44948 "EHLO mail.dvmed.net") by vger.kernel.org with ESMTP id S1751283AbWBOUVt (ORCPT ); Wed, 15 Feb 2006 15:21:49 -0500 In-Reply-To: <20060215151200.GW4203@suse.de> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Jens Axboe Cc: Tejun Heo , albertcc@tw.ibm.com, linux-ide@vger.kernel.org, Mark Lord Jens Axboe wrote: > On Thu, Feb 16 2006, Tejun Heo wrote: > >>Jens Axboe wrote: >> >>>On Wed, Feb 15 2006, Tejun Heo wrote: >>> >>> >>>>max_hw_sectors/max_sectors separation patch made into the tree, >>>>increase max_sectors to its hardware limit. >>>> >>>>Signed-off-by: Tejun Heo >>>> >>>>--- >>>> >>>>Jeff, first of all, thanks for the pointer. I have two more >>>>questions. >>>> >>>>* I make ATA_MAX_SECTORS_LBA48 65535 (the 0000h case is supposed to be >>>>broken, right?); however, the comment says 65534. Should it be >>>>65534? >>> >>> >>>Since we never noticed any breakage on !sectors on lba28, I think we can >>>safely assume that !sectors will work fine for lba48 as well. So why not >>>just make it full 64k, eg 65536? ->max_hw_sectors is an unsigned int >>>now, so 64k wont overflow it. >>> >> >>Hello, Jens. >> >>libata currently sets max_sectors to 200 (ATA_MAX_SECTORS) on lba28. >>Are you talking about IDE driver? IDE driver seems to set max_sectors >>to 256 on probe and make it 2048 while setting up ide disk if lba48. > > > Yes I mean the IDE driver. The 200 sector value in libata has always > struck me as being extremely odd and a very bad choice. It's somewhere > in between reasonable defaults, which isn't very nice. I'd suggest just > making it 256 as well, unless Jeff has a reason why it's set to 200. Its set to 200 for a libata-related reason that I now forget :( It had nothing to do with controllers or devices, hence the FIXME. As an aside, I wonder if the PRD limit is unnecessarily low. I don't remember seeing anything that claimed we were limited to 256 s/g entries in the old IDE docs? Jeff