Hi, Thank you for your reply.
On Friday, March 15, 2024 4:57:39 PM IST Eugenio Perez Martin wrote: > [...] > > Some sections in the above docs were difficult to grasp. For the time > > being, I have focused on those parts that I thought were relevant > > to the project. > > Please feel free to ask any questions, maybe we can improve the doc :). I understood the introductory sections of the documentation such as the "About QEMU" section and the first half of the "system emulation". Sections and subsections that went into greater detail were a little overwhelming such as the "QEMU virtio-net standby" subsection [1] or the "migration features" [2] subsection. But the red hat blogs and deep-dive articles helped cover a lot of ground conceptually. I feel once I start getting my hands dirty, I'll be able to absorb these concepts much better. I did have two questions that I would like to ask. Q1. Regarding the "Deep dive into Virtio-networking and vhost-net" article [3], the "Introduction" subsection of the "Vhost protocol" section mentions that sending the available buffer notification involves a vCPU interrupt (4th bullet point). But in figure 2, the arrow for the "available buffer notification" indicates a PCI interrupt. Initially I thought they were two different interrupts but I am a little confused about this now. Q2. In the "Virtio-net failover operation" section of the "Virtio-net failover: An introduction" article [4], there are five bullet points under the first figure. The second point states that the guest kernel needs the ability to switch between the VFIO device and the vfio-net device. I was wondering if "vfio-net" is a typo and if it should be "virtio-net" instead. > [...] > There is a post before the first in the series: > https://www.redhat.com/en/blog/virtio-devices-and-drivers-overview-headjack- > and-phone Got it. I didn't know this was the first in the series. I have now covered this as well, so I can move on to "Virtqueues and virtio ring: How the data travels" [3] :) > > 1. Virtqueues and virtio ring: How the data travels [8] > > 2. Packed virtqueue: How to reduce overhead with virtio [9] > > 3. Virtio live migration technical deep dive [10] > > 4. Hands on vDPA: what do you do when you ain't got the hardware v2 (Part > > 1) [11] > I think it's a good plan! > > If you feel like you're reading a lot of theory and want to get your > hands dirty already, you can also start messing with the code with the > blogs you already read. Or, maybe, after reading the Packed virtqueue > one, your call. > > In a very brute-forced description, you can start trying to copy all > the *packed* stuff of kernel's drivers/virtio/virtio_ring.c into > vhost_shadow_virtqueue.c. I would love to start with some hands-on tasks. I'll take a look at the kernel's "drivers/virtio/virtio_ring.c". I think I should also start going through the "vhost_shadow_virtqueue.c" [4] source code. > There is a lot more in the task, and I can get into more detail > if you want either here or in a meeting. Thank you. Either means of communication works for me although the latter will require some coordination. > If you prefer to continue with the theory it is ok too. A good balance of theory and practice would be nice at this stage. It'll keep my brains from getting too muddled up. Thanks, Sahil [1] https://www.qemu.org/docs/master/system/virtio-net-failover.html [2] https://www.qemu.org/docs/master/devel/migration/features.html [3] https://www.redhat.com/en/blog/deep-dive-virtio-networking-and-vhost-net [4] https://www.redhat.com/en/blog/virtio-net-failover-introduction [5] https://www.redhat.com/en/blog/virtqueues-and-virtio-ring-how-data-travels
