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Thu, 16 Jul 2026 07:31:55 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ThreadId: AnORdmDlkYiw Date: Thu, 16 Jul 2026 13:31:17 +0200 From: "Arnd Bergmann" To: "Krzysztof Kozlowski" , "Anshuman Khandual" , linux-arm-kernel@lists.infradead.org Cc: "Eric Biggers" , "Linus Walleij" , "Alexandre Belloni" , linux-kernel@vger.kernel.org Message-Id: In-Reply-To: <2fae9ef8-2ec1-48ed-9b25-8526db625732@oss.qualcomm.com> References: <20260716100243.1604526-1-anshuman.khandual@arm.com> <2fae9ef8-2ec1-48ed-9b25-8526db625732@oss.qualcomm.com> Subject: Re: [PATCH] arm64/defconfig: Restore built-in 9P rootfs support Content-Type: text/plain Content-Transfer-Encoding: 7bit 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, 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. 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. Arnd