From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52247) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZB1kq-0003zl-Ux for qemu-devel@nongnu.org; Fri, 03 Jul 2015 10:15:49 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZB1kl-0001Oy-4x for qemu-devel@nongnu.org; Fri, 03 Jul 2015 10:15:48 -0400 Received: from cantor2.suse.de ([195.135.220.15]:41654 helo=mx2.suse.de) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZB1kk-0001M3-UK for qemu-devel@nongnu.org; Fri, 03 Jul 2015 10:15:43 -0400 Message-ID: <5596990C.5090204@suse.de> Date: Fri, 03 Jul 2015 16:15:40 +0200 From: Hannes Reinecke MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Subject: [Qemu-devel] SATA CD-ROM booting failure with latest OVMF List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: John Snow Cc: "qemu-devel@nongnu.org" , Alexander Graf Hi all, I've updated OVMF to use the SATA controller, so that I could finally use the Q35 machine specification with OVMF. However, upon doing so I found that the (SATA) CD-ROM wouldn't work anymore; directories on the CD-ROM can be read, but the file listing contained only garbage. After some _very_ tedious debugging I've found this to be an issue with the ahci driver in qemu; ATAPI PIO transfers seem to be slightly buggy. Enabling 'atapi_dma' transfers in atapi driver (even for PIO mode) makes everything work again. I still fail to see _why_ this is be the case; the logfiles in both cases are pretty identical. Originally I thought that somehow the big qemu lock plays a role here, but OVMF accesses the ahci HBA only ever _after_ all transfers are complete. And again, access patterns are identical in both cases. So if anyone has another idea here ... Cheers, Hannes --=20 Dr. Hannes Reinecke zSeries & Storage hare@suse.de +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N=C3=BCrnberg GF: F. Imend=C3=B6rffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton HRB 21284 (AG N=C3=BCrnberg)