From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id BA9F6C54E49 for ; Fri, 23 Feb 2024 10:25:40 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rdSjU-0001f8-Na; Fri, 23 Feb 2024 05:24:44 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rdSjS-0001es-AX for qemu-devel@nongnu.org; Fri, 23 Feb 2024 05:24:42 -0500 Received: from fout5-smtp.messagingengine.com ([103.168.172.148]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rdSjP-0008S6-VO for qemu-devel@nongnu.org; Fri, 23 Feb 2024 05:24:42 -0500 Received: from compute6.internal (compute6.nyi.internal [10.202.2.47]) by mailfout.nyi.internal (Postfix) with ESMTP id C022B13800A5; Fri, 23 Feb 2024 05:24:36 -0500 (EST) Received: from mailfrontend1 ([10.202.2.162]) by compute6.internal (MEProxy); Fri, 23 Feb 2024 05:24:36 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=irrelevant.dk; h=cc:content-type:content-type:date:date:from:from:in-reply-to :message-id:mime-version:reply-to:subject:subject:to:to; s=fm3; t=1708683876; x=1708770276; bh=WWEo1IMUSNdbN/to8orlTB/j9PdB8Jbh rrSo2TGsJUE=; b=RXN1VLKjxVcJUPaCuBQoWdxBo5vAv467PFPuccGahiWKDIu0 SMr8OwhTmm7NqiUjYcOZDJERjqbEQIWi+TdlpsNOf6AnvWvIIyh8FofpyfLGZPjl 9xL4aX+TRbRAeVb91FCQ+1n8GWe4FxopQsO4AYxE379gG67wHZM6sQls9urQyjnZ mwD2rlDWkxdiYOnEfC9axEhUgTKEaiL8cejo8x287J4L/DMAPL/vr0qUr5W3m81/ L9MY0nqrHJCIKE+Pj26Wv2Y2AsUidMbvloPRj/sIFB2UzS5Icvnk/MpsX29cr03O gK2Cvkw+uIIkrzryOK8X2FQynSqj4uEH9ZyCkw== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-type:content-type:date:date :feedback-id:feedback-id:from:from:in-reply-to:message-id :mime-version:reply-to:subject:subject:to:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm1; t= 1708683876; x=1708770276; bh=WWEo1IMUSNdbN/to8orlTB/j9PdB8JbhrrS o2TGsJUE=; b=bZVbc7+zgaO+NyKXc5Sh/n3zf+tvZCHXyZeuuOgIXltshJj200E BjRW0p4bCXSowh+XoMWpGpjrHoYR7KY3KyYVLi6AQ+c4blg52YAkaO9b31BN2v/p CuYRzSkFVwK0vUFelui13d37m1CRL6JwKJ5eruG6KmolMmuSNtgbXBK2ISZ0JfzL bzkMt/U7LgdWCgbr449FgicQcQg1ognV4jR9DMAQnB2PqwlNNiM2e/A5QvMzGNlp xGSgT4ArHRqNcHtvXQuWlR1uTMmm9mzGwDHfu+NjVSenNflvSyrZ+jb3aLBz+Acu nY1vF8cN7cuRl4620+bczWQgvsMK3/tmKmw== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvledrfeeigdduhecutefuodetggdotefrodftvf curfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfghnecu uegrihhlohhuthemuceftddtnecunecujfgurhepfffhvffukfggtggusehgtderredttd ejnecuhfhrohhmpefmlhgruhhsucflvghnshgvnhcuoehithhssehirhhrvghlvghvrghn thdrughkqeenucggtffrrghtthgvrhhnpedvuefgkeffhedvkefhueegkeeukeegieetve eihfeuuedutdfhudethfdvvedtudenucffohhmrghinhepghhithhlrggsrdgtohhmnecu vehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehmrghilhhfrhhomhepihhtshesih hrrhgvlhgvvhgrnhhtrdgukh X-ME-Proxy: Feedback-ID: idc91472f:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Fri, 23 Feb 2024 05:24:35 -0500 (EST) Date: Fri, 23 Feb 2024 11:24:31 +0100 From: Klaus Jensen To: qemu-devel@nongnu.org Subject: Clarification on cross-version compatibility requirements Message-ID: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="FQoOh2UGzWE75+Qx" Content-Disposition: inline Received-SPF: pass client-ip=103.168.172.148; envelope-from=its@irrelevant.dk; helo=fout5-smtp.messagingengine.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org --FQoOh2UGzWE75+Qx Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Hi all, Yesterday, a bug but in hw/nvme (#2184) was filed https://gitlab.com/qemu-project/qemu/-/issues/2184) The reporter ran into an issue with hibernating a guest from QEMU v4.1.0 and trying to resume it on v8.2.1. hw/nvme has received some changes since then, including a change in the BAR layout which causes the boot to fail. Now, hw/nvme is marked 'unmigratable'. I realize that this is only observed and checked under live migration, but I honestly did not know that hw/nvme were expected to ensure that the kind of "hibernation migration" works. I already have a potential fix for the issue (because I don't just want to say "wontfix", I'd like to fix it), but it got me thinking about what the general requirements are. And I couldn't find any good documentation on it. So, my question is: when is an emulated device required to support such version compatibility? I'm asking because we've also deprecated some stuff, like the device originally using an internal Intel PCI device id that we wanted to get rid of. But now, I don't think I can actually remove that parameter, I need to keep it around for hw/core/machine.c to set if necessary. Can anyone enlighten me on the guidelines (de-facto requirements) for this? Thanks, Klaus --FQoOh2UGzWE75+Qx Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCgAdFiEEUigzqnXi3OaiR2bATeGvMW1PDekFAmXYcl4ACgkQTeGvMW1P Denf1Qf/RFmDUD6F0nv8r4U//3xAyCHhlQAndu3M7Wk2v1CarNb4JToRn25dJvxP anynsaFbWKxq2mTXzzduRgRorgoxXh0X2GM0bVdUQ12t/y1ym2AxtbZw6015gwy4 pleR5ijovFs3PRQHAm4YyZfQ0JFL50JpEfj746+Da9SugcSm5RMNlHToGVZYsm88 7JR1lLbeM5gJMrWanTQanKRBHJFSFoIQVqIPOBoeowgn9GgWAv44jdAjSzpInqng ySsIu6PTa9W0++HMMSXwrFbXcpYNDdVGNrvUuITsM0unWqUfP1PwP69KLQbDD49g OyINWtld+tMNHeTCnvY8cII7pES20g== =BktK -----END PGP SIGNATURE----- --FQoOh2UGzWE75+Qx--