Jing Liu <jing2....@linux.intel.com> writes: > Hi Sergio, > > On 8/29/2019 11:46 PM, Sergio Lopez wrote: >> >> Jing Liu <jing2....@linux.intel.com> writes: >> >>> Hi Sergio, >>> >>> The idea is interesting and I tried to launch a guest by your >>> guide but seems failed to me. I tried both legacy and normal modes, >>> but the vncviewer connected and told me that: >>> The vm has no graphic display device. >>> All the screen in vnc is just black. >> >> The microvm machine type doesn't support any graphics device, so you >> need to rely on the serial console. > Got it. > >> >>> kernel config: >>> CONFIG_KVM_MMIO=y >>> CONFIG_VIRTIO_MMIO=y >>> >>> I don't know if any specified kernel version/patch/config >>> is needed or anything I missed. >>> Could you kindly give some tips? >> >> I'm testing it with upstream vanilla Linux. In addition to MMIO, you >> need to add support for PVH (the next version of this patchset, v4, will >> support booting from FW, so it'll be possible to use non-PVH ELF kernels >> and bzImages too). >> >> I've just uploaded a working kernel config here: >> >> https://gist.github.com/slp/1060ba3aaf708584572ad4109f28c8f9 >> > Thanks very much and this config is helpful to me. > >> As for the QEMU command line, something like this should do the trick: >> >> ./x86_64-softmmu/qemu-system-x86_64 -smp 1 -m 1g -enable-kvm -M >> microvm,legacy -kernel vmlinux -append "earlyprintk=ttyS0 console=ttyS0 >> reboot=k panic=1" -nodefaults -no-user-config -nographic -serial stdio >> >> If this works, you can move to non-legacy mode with a virtio-console: >> >> ./x86_64-softmmu/qemu-system-x86_64 -smp 1 -m 1g -enable-kvm -M microvm >> -kernel vmlinux -append "console=hvc0 reboot=k panic=1" -nodefaults >> -no-user-config -nographic -serial pty -chardev stdio,id=virtiocon0,server >> -device virtio-serial-device -device virtconsole,chardev=virtiocon0 >> > I tried the above two ways and it works now. Thanks! > >> If is still working, you can try adding some devices too: >> >> ./x86_64-softmmu/qemu-system-x86_64 -smp 1 -m 1g -enable-kvm -M microvm >> -kernel vmlinux -append "console=hvc0 reboot=k panic=1 root=/dev/vda" >> -nodefaults -no-user-config -nographic -serial pty -chardev >> stdio,id=virtiocon0,server -device virtio-serial-device -device >> virtconsole,chardev=virtiocon0 -netdev user,id=testnet -device >> virtio-net-device,netdev=testnet -drive >> id=test,file=alpine-rootfs-x86_64.raw,format=raw,if=none -device >> virtio-blk-device,drive=test >> > But I'm wondering why the image I used can not be found. > root=/dev/vda3 and the same image worked well on normal qemu/guest- > config bootup, but didn't work here. The details are, > > -append "console=hvc0 reboot=k panic=1 root=/dev/vda3 rw rootfstype=ext4" \ > > [ 0.022784] Key type encrypted registered > [ 0.022988] VFS: Cannot open root device "vda3" or > unknown-block(254,3): error -6 > [ 0.023041] Please append a correct "root=" boot option; here are > the available partitions: > [ 0.023089] fe00 8946688 vda > [ 0.023090] driver: virtio_blk > [ 0.023143] Kernel panic - not syncing: VFS: Unable to mount root > fs on unknown-block(254,3) > [ 0.023201] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.3.0-rc3 #23 > > > BTW, root=/dev/vda is also tried and didn't work. The dmesg is a > little different: > > [ 0.028050] Key type encrypted registered > [ 0.028484] List of all partitions: > [ 0.028529] fe00 8946688 vda > [ 0.028529] driver: virtio_blk > [ 0.028615] No filesystem could mount root, tried: > [ 0.028616] ext4 > [ 0.028670] > [ 0.028712] Kernel panic - not syncing: VFS: Unable to mount root > fs on unknown-block(254,0) > > I tried another ext4 img but still doesn't work. > Is there any limitation of blk image? Could I copy your image for simple > test?
The kernel config I posted lacks support for DOS partitions. Adding CONFIG_MSDOS_PARTITION=y should allow you to boot from /dev/vda3. Anyway, in case you also want to try booting from /dev/vda (without partitions), this is the recipe I use to quickly create a minimal rootfs image: # wget http://dl-cdn.alpinelinux.org/alpine/v3.10/releases/x86_64/alpine-minirootfs-3.10.2-x86_64.tar.gz # qemu-img create -f raw alpine-rootfs-x86_64.raw 1G # sudo losetup /dev/loop0 alpine-rootfs-x86_64.raw # sudo mkfs.ext4 /dev/loop0 # sudo mount /dev/loop0 /mnt # sudo tar xpf alpine-minirootfs-3.10.2-x86_64.tar.gz -C /mnt # sudo umount /mnt # sudo losetup -d /dev/loop0 The rootfs will be missing openrc, so you'll need to add "init=/bin/sh" to the command line. Sergio. > Thanks in advance, > Jing > >> Sergio. >> >>> Thanks very much. >>> Jing >>> >>> >>> >>>> A QEMU instance with the microvm machine type can be invoked this way: >>>> >>>> - Normal mode: >>>> >>>> qemu-system-x86_64 -M microvm -m 512m -smp 2 \ >>>> -kernel vmlinux -append "console=hvc0 root=/dev/vda" \ >>>> -nodefaults -no-user-config \ >>>> -chardev pty,id=virtiocon0,server \ >>>> -device virtio-serial-device \ >>>> -device virtconsole,chardev=virtiocon0 \ >>>> -drive id=test,file=test.img,format=raw,if=none \ >>>> -device virtio-blk-device,drive=test \ >>>> -netdev tap,id=tap0,script=no,downscript=no \ >>>> -device virtio-net-device,netdev=tap0 >>>> >>>> - Legacy mode: >>>> >>>> qemu-system-x86_64 -M microvm,legacy -m 512m -smp 2 \ >>>> -kernel vmlinux -append "console=ttyS0 root=/dev/vda" \ >>>> -nodefaults -no-user-config \ >>>> -drive id=test,file=test.img,format=raw,if=none \ >>>> -device virtio-blk-device,drive=test \ >>>> -netdev tap,id=tap0,script=no,downscript=no \ >>>> -device virtio-net-device,netdev=tap0 \ >>>> -serial stdio >>>> >>
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