Tag Archives: qemu

Fedora/RISC-V: Runnable stage 4 disk images

We’ve now got:

  1. An autobuilder.
  2. A multithreaded QEMU.
  3. A Fedora RPMs repository.
  4. A bootable disk image.

It’s unpolished and minimal at the moment, but what you can do today (if you have a Fedora 27+ x86_64 host):

  1. Enable the rjones/riscv copr and install riscv-qemu.
  2. Download the stage4-disk.img, and bbl and uncompress the disk image.
  3. Run this command:
    qemu-system-riscv64 \
        -nographic -machine virt -m 2G -smp 4 \
        -kernel bbl \
        -append "console=ttyS0 ro root=/dev/vda init=/init" \
        -device virtio-blk-device,drive=hd0 \
        -drive file=stage4-disk.img,format=raw,id=hd0 \
        -device virtio-net-device,netdev=usernet \
        -netdev user,id=usernet
    
  4. Inside the guest drop a repo file into /etc/yum.repos.d containing:
    [local]
    name=RPMS
    baseurl=https://fedorapeople.org/groups/risc-v/RPMS/
    enabled=1
    gpgcheck=0
    
  5. Use tdnf --releasever 27 install ... to install more packages.
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Fedora/RISC-V: the final bootstrap

There are bootable (but very minimal) disk images built cleanly from RPMs: https://fedorapeople.org/groups/risc-v/disk-images/

More soon …

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Tip: Changing the qemu product name in libguestfs

20:30 < koike> Hi. Is it possible to configure the dmi codes for libguestfs? I mean, I am running cloud-init inside a libguestfs session (through python-guestfs) in GCE, the problem is that cloud-init reads /sys/class/dmi/id/product_name to determine if the machine is a GCE machine, but the value it read is Standard PC (i440FX + PIIX, 1996) instead of the expected Google Compute Engine so cloud-init fails.

The answer is yes, using the guestfs_config API that lets you set arbitrary qemu parameters:

g.config('-smbios',
         'type=1,product=Google Compute Engine')

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virt-builder Debian 9 image available

Debian 9 (“Stretch”) was released last week and now it’s available in virt-builder, the fast way to build virtual machine disk images:

$ virt-builder -l | grep debian
debian-6                 x86_64     Debian 6 (Squeeze)
debian-7                 sparc64    Debian 7 (Wheezy) (sparc64)
debian-7                 x86_64     Debian 7 (Wheezy)
debian-8                 x86_64     Debian 8 (Jessie)
debian-9                 x86_64     Debian 9 (stretch)

$ virt-builder debian-9 \
    --root-password password:123456
[   0.5] Downloading: http://libguestfs.org/download/builder/debian-9.xz
[   1.2] Planning how to build this image
[   1.2] Uncompressing
[   5.5] Opening the new disk
[  15.4] Setting a random seed
virt-builder: warning: random seed could not be set for this type of guest
[  15.4] Setting passwords
[  16.7] Finishing off
                   Output file: debian-9.img
                   Output size: 6.0G
                 Output format: raw
            Total usable space: 3.9G
                    Free space: 3.1G (78%)

$ qemu-system-x86_64 \
    -machine accel=kvm:tcg -cpu host -m 2048 \
    -drive file=debian-9.img,format=raw,if=virtio \
    -serial stdio

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Supernested on the QEMU Advent Calendar

screenshot_2016-12-13_08-51-04

I wrote supernested a few years ago to see if I could break nested KVM. It works by repeatedly nesting KVM guests until either something breaks or the whole thing grinds to a halt. Even on my very fastest machine I can only get to an L4 guest (L0 = host, L1 = normal guest).

Kashyap and Thomas Huth resurrected the QEMU Advent Calendar this year, and today (day 13) supernested is featured.

Please note that supernested should only be run on idle machines which aren’t doing anything else, and it can crash the machine.

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Fedora 25 is out, virt-builder images available

$ virt-builder -l | grep fedora-25
fedora-25                x86_64     Fedora® 25 Server
fedora-25                i686       Fedora® 25 Server (i686)
fedora-25                aarch64    Fedora® 25 Server (aarch64)
fedora-25                armv7l     Fedora® 25 Server (armv7l)
fedora-25                ppc64      Fedora® 25 Server (ppc64)
fedora-25                ppc64le    Fedora® 25 Server (ppc64le)
$ virt-builder fedora-25
$ qemu-system-x86_64 -machine accel=kvm:tcg \
      -cpu host -m 2048 \
      -drive file=fedora-25.img,format=raw,if=virtio

Or to try out Fedora on a different architecture:

$ virt-builder fedora-25 --arch ppc64le -o fedora-25-ppc64le.img
$ qemu-system-ppc64 -cpu POWER8 -m 2048 \
      -drive file=fedora-25-ppc64le.img,format=raw,if=virtio

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Now building Fedora/RISC-V “stage4” disk images

I’m happy to announce that Fedora/RISC-V, the project to bootstrap Fedora on the new RISC-V architecture, has reached a key milestone: We are now releasing clean “stage4” disk images which are built entirely from RPMs (ie. every file except two[1] are managed by RPM).

You can get the latest image from http://oirase.annexia.org/riscv/

To use it, you must enable my RISC-V tools copr:

# dnf copr enable rjones/riscv
# dnf install riscv-qemu riscv-pk

and you can then boot the stage4 directly using this qemu command[2]:

$ qemu-system-riscv -m 4G -kernel /usr/bin/bbl \
    -append vmlinux \
    -drive file=stage4-disk.img,format=raw -nographic

This is an early release and there are a few problems. The main one is that we lack a util-linux package, and thus there is no mount command so the disk image stays read-only after boot. You’ll see lots of errors like this at boot:

/init: line 16: mount: command not found
/init: line 19: mount: command not found
/init: line 20: mount: command not found

I hope to get that fixed soon.

There’s also no actual rpm command in the stage4, again because of a required dependency, and again that’s something that will be fixed real soon.

Many thanks go to David Abdurachmanov and Stefan O’Rear for their huge efforts building packages.

Notes:

[1] Because there is no systemd package yet, currently two extra files are added to the disk image which are not under the control of RPM: /init and /usr/bin/poweroff

[2] For real hardware, read this page

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