From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: [PATCH] libata: increase LBA48 max sectors to 65535 Date: Wed, 15 Feb 2006 16:12:01 +0100 Message-ID: <20060215151200.GW4203@suse.de> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from ns.virtualhost.dk ([195.184.98.160]:33567 "EHLO virtualhost.dk") by vger.kernel.org with ESMTP id S1945971AbWBOPM6 (ORCPT ); Wed, 15 Feb 2006 10:12:58 -0500 Content-Disposition: inline In-Reply-To: <43F342E6.9060909@gmail.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Tejun Heo Cc: Jeff Garzik , albertcc@tw.ibm.com, linux-ide@vger.kernel.org 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. > Hmmm... Can we really trust all the firmwares? I just feel that some > drive out there ought have screwed up about nsect == 00h/0000h case. Apparently Windows uses it, so I'd say that should pretty much guarantee that it will work for us. And as I mentioned, there has never been a case where the IDE driver value of 256 triggered a drive bug (one time one was suspected, it turned out to be something else though). -- Jens Axboe