From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39015) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gUZUi-0006jV-F5 for qemu-devel@nongnu.org; Wed, 05 Dec 2018 10:53:49 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gUZUe-0001QT-BX for qemu-devel@nongnu.org; Wed, 05 Dec 2018 10:53:48 -0500 Received: from mx1.redhat.com ([209.132.183.28]:55408) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gUZUe-0001Pg-5P for qemu-devel@nongnu.org; Wed, 05 Dec 2018 10:53:44 -0500 Date: Wed, 5 Dec 2018 08:53:38 -0700 From: Alex Williamson Message-ID: <20181205085338.358dc9bd@x1.home> In-Reply-To: <87y394wd9p.fsf@dusky.pond.sub.org> References: <154393964026.28192.13536237934563059985.stgit@gimli.home> <154394077749.28192.1229512133780284321.stgit@gimli.home> <87y394wd9p.fsf@dusky.pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [for-4.0 PATCH v3 3/9] qapi: Define PCIe link speed and width properties List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Markus Armbruster Cc: qemu-devel@nongnu.org, Geoffrey McRae On Wed, 05 Dec 2018 10:09:38 +0100 Markus Armbruster wrote: > Alex Williamson writes: >=20 > > Create properties to be able to define speeds and widths for PCIe > > links. The only tricky bit here is that our get and set callbacks > > translate from the fixed QAPI automagic enums to those we define > > in PCI code to represent the actual register segment value. =20 >=20 > QAPI can only generate enumerations with values 0, 1, 2, ... You want > different enumeration values, namely the actual register values. You > still want QAPI to get its standard mapping to and from strings. >=20 > This patch's solution is to define a non-QAPI enumeration type with the > values you want [PATCH 1/9], then map between the enumerations in the > PropertyInfo methods. Works. >=20 > You could instead use the encoding chosen by QAPI for the properties, > and map it to the register values on use. Differently ugly. Might be > simpler. Your choice to make. As we discussed offline, I personally don't like using the magic macros that QAPI generates outside of QAPI code; I can't git grep for them and I need to remember to build the tree before using cscope in order to find them. Therefore I prefer to keep the translation to standard macros within the QAPI code to make things more obvious, thus the approach chosen. I appreciate the feedback and alternative ideas. > We could extend QAPI to permit specification of the enumeration values. > Marc-Andr=C3=A9's work to permit conditionals makes the syntax flexible > enough to support that. Of course, adding QAPI features is worthwhile > only if we get sufficient mileage out of them to result in an overall > improvement. Even if we decided to do it right now, I'd recommend not > to wait for it, but instead plan to simplify after the feature lands. Good to know. > > Cc: Eric Blake > > Cc: Markus Armbruster > > Tested-by: Geoffrey McRae > > Signed-off-by: Alex Williamson =20 >=20 > Reviewed-by: Markus Armbruster Thanks! Alex