Re: Intention to work on GSoC project

[Sahil <icegambit91@gmail.com>]

Hi,

On Friday, April 5, 2024 12:36:02 AM IST Sahil wrote:
> [...] 
> I'll set up this environment as well.

I would like to post an update here. I spent the last week 
trying to set up the environment as described in the blog [1].
I initially tried to get the L1 VM running on my host machine
(Arch Linux). However,  I was unable to use virt-sysprep or
virt-cutomize to install packages in the qcow2 image. It wasn't
able to resolve the hosts while downloading the packages.

According to the logs, /etc/resolv.conf was a dangling symlink.
I tried to use "virt-rescue" to configure DNS resolution. I tried
following these sections [2], [3] in the Arch wiki but that didn't
work either. I tried using qemu-nbd as well following this section
[4] to access the image. While I managed gain access to the
image, I wasn't able to install packages after performing a
chroot.

One workaround was to set this environment up in a VM. I
decided to set up the environment with a Fedora image in
virtualbox acting as L0. I have managed to set up an L1 VM
in this environment and I can load it using qemu-kvm.

I have one question though. One of the options (use case 1 in [1])
given to the "qemu-kvm" command is:
> -device virtio-net-pci,netdev=vhost-vdpa0,bus=pcie.0,addr=0x7\
> ,disable-modern=off,page-per-vq=on

This gives an error:
> Bus "pcie.0" not found

Does pcie refer to PCI Express? Changing this to pci.0 works.
I read through the "device buses" section in QEMU's user
documentation [5], but I have still not understood this. 

"ls /sys/bus/pci/devices/* | grep vdpa" does not give any results.
Replacing pci with pci_express doesn't give any results either. How
does one know which pci bus the vdpa device is connected to?
I have gone through the "vDPA bus drivers" section of the "vDPA
kernel framework" article [6] but I haven't managed to find an
answer yet. Am I missing something here?

There's one more thing. In "use case 1" of "Running traffic with
vhost_vdpa in Guest" [1], running "modprobe pktgen" in the L1 VM
gives an error:
> module pktgen couldn't be found in /lib/modules/6.5.6-300.fc39.x86_64.

The kernel version is 6.5.6-300.fc39.x86_64. I haven't tried building
pktgen manually in L1. I'll try that and will check if vdpa_sim works
as expected after that.

[1] https://www.redhat.com/en/blog/hands-vdpa-what-do-you-do-when-you-aint-got-hardware-part-1
[2] https://wiki.archlinux.org/title/QEMU#User-mode_networking
[3] https://wiki.archlinux.org/title/Systemd-networkd#Required_services_and_setup
[4] https://wiki.archlinux.org/title/QEMU#Mounting_a_partition_from_a_qcow2_image
[5] https://qemu-project.gitlab.io/qemu/system/device-emulation.html
[6] https://www.redhat.com/en/blog/vdpa-kernel-framework-part-1-vdpa-bus-abstracting-hardware

Thanks,
Sahil