From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35512) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eqLvO-0006uV-RZ for qemu-devel@nongnu.org; Mon, 26 Feb 2018 11:46:51 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eqLvL-0004JZ-NI for qemu-devel@nongnu.org; Mon, 26 Feb 2018 11:46:50 -0500 From: Alberto Garcia In-Reply-To: <09a1d661-14ce-3fe0-e3b6-2ce6d4e34348@redhat.com> References: <20180222155922.9833-1-eblake@redhat.com> <20180222155922.9833-3-eblake@redhat.com> <09a1d661-14ce-3fe0-e3b6-2ce6d4e34348@redhat.com> Date: Mon, 26 Feb 2018 17:46:44 +0100 Message-ID: MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [Qemu-devel] [PATCH v3 2/4] qcow2: Document some maximum size constraints List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eric Blake , qemu-devel@nongnu.org Cc: kwolf@redhat.com, qemu-block@nongnu.org, Max Reitz On Mon 26 Feb 2018 05:41:54 PM CET, Eric Blake wrote: >> But refcount blocks are not addressed by L2 tables, so in principle >> it should be possible to have refcount blocks after the first 64PB. > > But (if we don't make this change) that's about all you can usefully > have (and it would be a self-referencing refcount block). Yeah, true. >>> + 56 - 63: Reserved (set to 0) >> >> Are we not updating REFT_OFFSET_MASK as well? > > We could, but that should be a separate patch from the spec change. > We could also add some validation that any offsets in the header point > to less than the 64PB limit. Ok, let's leave that for another patch then. Reviewed-by: Alberto Garcia Berto