From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57583) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XjH75-0001J2-TK for qemu-devel@nongnu.org; Tue, 28 Oct 2014 20:27:56 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XjH6w-0003M9-OC for qemu-devel@nongnu.org; Tue, 28 Oct 2014 20:27:47 -0400 Received: from mail-wi0-x229.google.com ([2a00:1450:400c:c05::229]:42777) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XjH6w-0003M5-HP for qemu-devel@nongnu.org; Tue, 28 Oct 2014 20:27:38 -0400 Received: by mail-wi0-f169.google.com with SMTP id n3so313120wiv.0 for ; Tue, 28 Oct 2014 17:27:37 -0700 (PDT) Sender: Paolo Bonzini Message-ID: <54503475.6050500@redhat.com> Date: Wed, 29 Oct 2014 01:27:33 +0100 From: Paolo Bonzini MIME-Version: 1.0 References: <1412204151-18117-1-git-send-email-jsnow@redhat.com> <20141028135151.GC22805@stefanha-thinkpad.redhat.com> <54502CA1.1040802@redhat.com> <54502EE4.3090704@redhat.com> <54502F9B.2070901@redhat.com> In-Reply-To: <54502F9B.2070901@redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 0/6] AHCI Device Fixes List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: John Snow , Stefan Hajnoczi Cc: kwolf@redhat.com, armbru@redhat.com, qemu-devel@nongnu.org, stefanha@redhat.com, mst@redhat.com >> Yeah, I was wondering if any commands could have <512 bytes response... >> I sort of convinced myself that the answer was no for ATA commands, but >> stupidly forgot about packet (SCSI) commands. Their results are >> obviously shorter than 512 bytes. > > Are you referencing the sglist underflow patch? (#5 instead of #3) Hmm, yeah. > There were cases in the code already where we /assumed/ that having any bytes > implied we had at least a sector's worth. Even for ATAPI? If there are valid cases for > the sglist to have less than a sector's worth (SCSI) then I'll need to > touch that again as well and update all the assumptions in the IDE code > to look for numbytes instead of numsectors. cmd_inquiry can return 36 bytes. That can be both PIO and DMA. SeaBIOS only uses the DMA variant for AHCI. Paolo