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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 9FC29C4450F for ; Fri, 17 Jul 2026 04:16:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=RvcqjcKD2k24eeG1X+IgiTsgr1jJ4CBmmqIvgaG6pRU=; b=Jo/OKPdBV64Kd57i2c9OEjsAMj zj+SnFX41yFvUfCLY0MkIQnTA2N0X6iEzjMNNsNUAxhQoMyuQ6lhWDIHc4IFoQF4rK6uPj5U0bJEl bxmyMSj5VqGTCWOQS7kW0r65a9aT/MK+2kMqW2uXi/Uv7yg82esp4rIlZScG8VjhtV05GaGx5xzEk ON+62MFzpCt8UQZVwh3H252bx8/cDUQ19+Qq9JlDAMVKG9dnOcLlI+jbi1gl0Yse5X50wzOsuUAwW dYbcUNWVNP6OLnIs4DCDZeicO8C+HdCzpsf63yQ5DCvn9l8w67T+3xJYMdRDHNzcVo1w3lbL7+vK8 kPCLczMw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wka01-0000000170U-04Fy; Fri, 17 Jul 2026 04:16:33 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wkZzy-00000001705-3kPU for linux-arm-kernel@lists.infradead.org; Fri, 17 Jul 2026 04:16:32 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 207651476; Thu, 16 Jul 2026 21:16:25 -0700 (PDT) Received: from [10.164.18.90] (unknown [10.164.18.90]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 562023F7D8; Thu, 16 Jul 2026 21:16:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1784261789; bh=qbRRlxOtRN6hWppRiqfYwDql1OvoKXqkARDwBGDBgBY=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=BBQA1azIq5p20nHyKyJX1ATjKM0CRuIaUkF0sGkJBbdJ7Cf55ezLmUl3KBCpVimjA y9Dv4lsQnL9UOtMFVZdlDyCENDDHnXXEaGnRIcaNtCngwdFrOqb+LGcgeU5UkBgwQJ 0/m1kIKdvfx2hl9pVtPkU+DK372qUVeyxRQfxmI0= Message-ID: <8f512add-b78f-49df-9239-274e7a9558ea@arm.com> Date: Fri, 17 Jul 2026 09:46:24 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] arm64/defconfig: Restore built-in 9P rootfs support To: Arnd Bergmann , Krzysztof Kozlowski , linux-arm-kernel@lists.infradead.org Cc: Eric Biggers , Linus Walleij , Alexandre Belloni , linux-kernel@vger.kernel.org References: <20260716100243.1604526-1-anshuman.khandual@arm.com> <2fae9ef8-2ec1-48ed-9b25-8526db625732@oss.qualcomm.com> Content-Language: en-US From: Anshuman Khandual In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260716_211631_147969_CA0DB06A X-CRM114-Status: GOOD ( 12.22 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 16/07/26 5:01 PM, Arnd Bergmann wrote: > On Thu, Jul 16, 2026, at 13:01, Krzysztof Kozlowski wrote: >> On 16/07/2026 12:02, Anshuman Khandual wrote: >>> Commit d521c4ca039f ("arm64: defconfig: Switch Ethernet drivers to modules") >>> had changed 9P and virtio-9P support from built-in to modular instead. This >>> breaks simple kvmtool boots using a 9P root filesystem without an initramfs >>> , because the kernel must mount root filesystem before it can load the 9P >> >> >> And that commit explained you must use initramfs. Nothing got broken, >> because there was never a promise that a recent, virtualized environment >> must work on defconfig without initramfs. >> >> You fully control your software, so just build initramfs which is >> absolutely trivial and we all moved on to that for arm64 long time ago. > > I still regularly boot KVM guests on arm64 without an initramfs, Actually that is a very normal use case particularly with KVM tool. > but I just use 'make kvm_guest.config', which turns on all the > commonly used virtio drivers as built-in. I wouldn't call > 9pfs root trivial without initramfs, configuring 9p built-in > is already complicated enough. Alright - fair enough. > > So I agree we don't need this patch, but there is a trivial > workaround for Anshuman in case he wants to avoid doing this. The following sequence does indeed solve this problem for now. make mrproper make defconfig make kvm_guest.config