From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1MmscS-00065q-MY for qemu-devel@nongnu.org; Sun, 13 Sep 2009 13:12:08 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1MmscN-000600-Jx for qemu-devel@nongnu.org; Sun, 13 Sep 2009 13:12:07 -0400 Received: from [199.232.76.173] (port=59355 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MmscN-0005zx-Bq for qemu-devel@nongnu.org; Sun, 13 Sep 2009 13:12:03 -0400 Received: from mtaout01-winn.ispmail.ntl.com ([81.103.221.47]:49613) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1MmscM-0003YY-MW for qemu-devel@nongnu.org; Sun, 13 Sep 2009 13:12:03 -0400 Date: Sun, 13 Sep 2009 18:13:07 +0100 From: Stuart Brady Subject: Re: [Qemu-devel] [PATCH] fdc: fix MAX_FD probelm Message-ID: <20090913171307.GA17269@miranda.arrow> References: <20090913144407.GA17024@miranda.arrow> <200909131542.AA00107@YOUR-BD18D6DD63.m1.interq.or.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200909131542.AA00107@YOUR-BD18D6DD63.m1.interq.or.jp> List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "TAKEDA, toshiya" Cc: qemu-devel@nongnu.org On Mon, Sep 14, 2009 at 12:42:32AM +0900, TAKEDA, toshiya wrote: > Dear Stuart and members, > > >I'm still slightly concerned that for machines with MAX_PHYSICAL_DRIVES > >set to 2, guests would see drives 2 and 3 as present, but with no disk > >inserted. Previously, though, I expect they would have been mirrors of > >drives 0 and 1, which is obviously worse! > > FD_DOR_SELMASK is not affected by MAX_PHYSICAL_DRIVES and is fixed to 3, > so I think drive 2 and 3 are not recognized as the mirror of 0 and 1. Agreed. (Just to clarify, my comment about mirrors of drives 2 and 3 was referring to the old code, when FD_DOR_SELMASK was affected by MAX_FD.) > Well, I also think it is better the user can select the physical drive > number, not only 2 but 0, 1 and 3. > But it will require the large scale patch, for example the block and > qemu option commands. The user should really be able to attach drives individually, and have only drive 3 connected, if they want... but that's a separate problem. > If this patch is acceptable for commit, I will reimplement PC-09 patch > based on it and in this time I hope I can fix the sence interrupt status. My only concern is that a guest OS might now reserve drive letters for drives 2 and 3, whereas before, it might have ignored those drives because it was not possible to select them. In reality, it seems a greater concern that without this patch, a guest OS might allow access to the mirrors of drives 0 and 1, potentially causing filesystem corruption. :-( Cheers, -- Stuart Brady