Alex RPi booting Xen - RPi4 is booting GDOM0 with Xen, opensrc boot chain. Uboot crashing hard for a small mistake. This will be a suitable reference for Xen. Needs SSD vs SD Card which is unstable for rootfs. Propose we adopt this.
Mathieu: order now due to supply issues: Alex I have 8 gig, but it is now out of stock.
Alex: Should we look more at Argo, Argo does something we did not cover. Argo has hypervisor mediated copy, only one copy. HV checks. How does this work in high bandwidth situation - block device?
Alex what is the minimum number of copies: Arnd there are normally 2-3 more than you think, is this a competing solution to virtio ? Alex: written for Xens parvirt it is not the default. They are keen to open it out to be portable. Arnd, imagine that virtio not built on virt-queue, believe Xen is based on page flipping. Alex changing permission to page? Arnd yes.
Alex: does address space disappear Arnd there are multiple ways
Alex: Do we need to learn a little more about Argo? Can’t take on work, but just gathering info.
Arnd Fatvirt queue: Adminvirt queues are not a replacement for fatVirtqueue. They are a way to add metadata communications to an existing queue. Adds 4th way to have out-of-band communication rather than doing it in config space. Config blobs. Posted for block devices such as TRIM etc. Spec allows this for any virtio device