PC Recycler

This page is read only. You can view the source, but not change it. Ask your administrator if you think this is wrong.

Install QEMU on your system.  Follow the instructions at the official QEMU site^.


1) go to Debian Quick Image Baker pre-baked images[[https://people.debian.org/~gio/dqib/]] — this contains all the latest build images for QEMU virtualization (including a RISC-V build).

2) When you get there, look for the link labeled: “Images for riscv64-virt” — clicking that link (Images for riscv64-virt[^]) will instantly begin the download of a (zip) file which is named very oddly, like a hash value (2baed3d2ab30e7a4ff39c7e587c8b16dce3885afb2dc047dae555a8bc13e is the current name).

3) Once you download it, you can unzip the contents to its own folder to keep everything organized.

The contents of that file are:

    image.qcow2 — image file
    initrd – linux stuff
     kernel – linux kernel
     readme.txt – readme provides command line for QEMU
     ssh_user_ecdsa_key 
     ssh_user_ed25519_key 
     ssh_user_rsa_key 

The readme contains the QEMU command that you can use to start virtual environment.
We Need Two Additional Files

We actually need two additional files which are the bios and the kernel files for RISC-V Linux.

    fw_jump.elf
    uboot.elf

These files are part of the Open Source Supervisor Binary Interface.

For more information you can learn about them at : 

GitHub - riscv-software-src/opensbi: RISC-V Open Source Supervisor Binary Interface[[https://github.com/riscv-software-src/opensbi/tree/master]]
Download uboot.elf & fw_jump.elf

You can actually download those two files and place them anywhere you want on your local computer.

RISC-V-Assembly-Language-Programming/Chapter 1/QEMU at main · Apress/RISC-V-Assembly-Language-Programming · GitHub[[https://github.com/Apress/RISC-V-Assembly-Language-Programming/tree/main/Chapter%201/QEMU]]

Make sure that when you download each file that you download the RAW file.  GitHub does a weird thing and will download them as odd text files if you don't use the RAW option.
Download To Your Local Machine

Just make sure you reference the full path to them (wherever you placed them on your machine) when you run the QEMU command below.

You can see those two files are referenced in the QEMU command below.

Note: There cannot be any spaces after the line-continuation-character (\).

I've broken the command up over lines so you can see each argument which is passed to the QEMU executable.  There is a separate EXE for each QEMU platform (riscv64, x86_64, etc.) 


qemu-system-riscv64 -machine 'virt' \
-cpu 'rv64' \
-m 1G -device virtio-blk-device,drive=hd \
-drive file=image.qcow2,if=none,id=hd \
-device virtio-net-device,netdev=net \
-netdev user,id=net,hostfwd=tcp::2222-:22 \
-bios /usr/lib/riscv64-linux-gnu/opensbi/generic/fw_jump.elf \
-kernel /usr/lib/u-boot/qemu-riscv64_smode/uboot.elf \
-object rng-random,filename=/dev/urandom,id=rng \
-device virtio-rng-device,rng=rng \
-nographic \
-append "root=LABEL=rootfs console=ttyS0"

Once you start the virtual environment login using :
root(username) and root (pwd)

Now you can install the build_essential packages so you can write assembly and link.
You are root so no need for sudo:
BAT

$ apt install build-essential

You can check that the Assembler (as) and the linker (ld) are installed after that, by doing the following which will give you the versions of each exe.
BAT

$ as --version

$ ld --version

--------------------------------------------------------------------------------------------------------

====Mounting Raw and qcow2 Images====
Posted on 15 July 2016 by Albert de Vera	

Mounting Raw and qcow2 images in order to inspect and use them doesn’t have to be difficult. After searching the internet, we found a couple of recommendations on how to do it. Here is what we did ourselves on an Ubuntu 16.04 Linux host.
Mounting The Raw Image

Associate the raw image with a loop device:

losetup /dev/loop0 image.raw

Map the partitions to loop devices:

kpartx -a /dev/loop0

You should be able to mount the partitions now:

mount /dev/mapper/loop0p1 /mnt/t01

where /mnt/t01 is a previously-existing mount point or directory.

For LVM partitions, determine the volume group name and activate it:

vgscan
vgchange -ay vg_volgroupname

Mount the desired logical volume:

mount /dev/mapper/vg_volgroupname-lg_logicalgroupname /mnt/t02

where /mnt/t02 is another pre-existing mount point or directory.
Unmounting The Raw Image

Unmount the previously mounted partitions:

umount /dev/t02
umount /dev/t01

Deactivate the volume group:

vgchange -an vg_volgroupname

Undo the mapping of the partitions to the loop devices:

kpartx -d /dev/loop0

Destroy the loop:

losetup -d /dev/loop0

Mounting The qcow2 Image

Here, we shall use the QEMU Network Block Device Driver for the purposes of mounting the qcow2 image.

First, load the nbd driver.

modprobe nbd max_part=63

Connect nbd to the image using qemu-nbd:

qemu-nbd -c /dev/nbd0 disk1.qcow2

Using fdisk, check the existing partitions. Mount the regular Linux partitions as is:

mount /dev/nbd0p1 /mnt/t01

For LVM partitions, associate a loopback device to the LVM partition:

losetup /dev/loop0 /dev/nbd0p2

See the LVM partitions under /dev/mapper:

ls -l /dev/mapper

You should also be able to display the logical partitions using lvdisplay and the volume groups with vgdisplay. Use vgchange as above to activate the volume group.

Mount the regular LVM partitions as usual:

mount /dev/mapper/vg_volgroupname-lv_logicalgroupname /mnt/t02

Unmounting the qcow2 Image

Unmount the partitions from the qcow2 image:

umount /mnt/t02
umount /mnt/t01

Deactivate the volume group:

vgchange -an vg_volgroupname

Remove the loopback device:

losetup -d /dev/loop0

Disconnect the nbd device:

qemu-nbd -d /dev/nbd0

Finally, remove the nbd kernel module:

rmmod nbd

We have successfully used the above procedures in mounting and unmounting raw and qcow2 images used in Linux KVM.

The procedures described above have been adapted for this article from these URLs:

    https://www.redhat.com/archives/linux-lvm/2008-June/msg00045.html
    http://alexeytorkhov.blogspot.com/2009/09/mounting-raw-and-qcow2-vm-disk-images.html

https://www.linuxunbound.com/2016/07/15/mounting-raw-and-qcow2-images/
PC Recycler

User Tools

Site Tools

Page Tools
