From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 6115F18AEB for ; Fri, 25 Aug 2023 18:25:05 +0000 (UTC) Received: from [192.168.0.5] (71-212-112-68.tukw.qwest.net [71.212.112.68]) by linux.microsoft.com (Postfix) with ESMTPSA id D00DA2127C95; Fri, 25 Aug 2023 11:24:58 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com D00DA2127C95 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1692987899; bh=lTiAq6TIQlz3/KRzBrYOW9Zloaa6S2j8QsR1OWQ9nd0=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=O7+HQDi40dbcU5ZJ+REsZOWEZbODS6aqRVj4DMw9c6KTpW6MGAoCJiEkoiHCN9+lb qeO/sDXHDMnr3G3VhGWUbUBoBwRvv009PLONJU70BqfDsHZJ+EUTSjer4YwBIGwRdZ jJPkTnenGtlRUjYJeGFRyc2zXJLb3eQBXaQU9Y1A= Message-ID: Date: Fri, 25 Aug 2023 11:24:58 -0700 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 13/15] uapi: hyperv: Add mshv driver headers hvhdk.h, hvhdk_mini.h, hvgdk.h, hvgdk_mini.h Content-Language: en-US To: Greg KH , Wei Liu Cc: linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org, linux-arm-kernel@lists.infradead.org, linux-arch@vger.kernel.org, patches@lists.linux.dev, mikelley@microsoft.com, kys@microsoft.com, haiyangz@microsoft.com, decui@microsoft.com, apais@linux.microsoft.com, Tianyu.Lan@microsoft.com, ssengar@linux.microsoft.com, mukeshrathor@microsoft.com, stanislav.kinsburskiy@gmail.com, jinankjain@linux.microsoft.com, vkuznets@redhat.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, will@kernel.org, catalin.marinas@arm.com References: <1692309711-5573-1-git-send-email-nunodasneves@linux.microsoft.com> <1692309711-5573-14-git-send-email-nunodasneves@linux.microsoft.com> <2023081923-crown-cake-79f7@gregkh> From: Nuno Das Neves In-Reply-To: <2023081923-crown-cake-79f7@gregkh> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 8/19/2023 3:26 AM, Greg KH wrote: > > My "strong" opinion is the one kernel development rule that we have, > "you can not break userspace". So, if you change these > values/structures/whatever in the future, and userspace tools break, > that's not ok and the changes have to be reverted. > > If you can control both sides of the API here (with open tools that you > can guarantee everyone will always update to), then yes, you can change > the api in the future. > This is true for us - we contribute and maintain support for this driver in Cloud Hypervisor[1], an open source VMM. We also do a check of the hypervisor version when the driver loads, and refuse to proceed if it is running on an incompatible hypervisor. Thanks, Nuno Das Neves [1] https://github.com/cloud-hypervisor/cloud-hypervisor