On Sun, 19 Jan 2025 at 21:02, Dmitry Osipenko <dmitry.osipe...@collabora.com> wrote: > I've tested this patch. Partial mapping with a non-zero offset doesn't > work because drm_gem_mmap() rejects it. I'd want to see your sample code > that performs mmaping, maybe I'm missing something.
The entire setup is a huge pile of moving parts, but here is the relevant function that creates a fd from the cross domain info (this is a part of the vm agent) https://github.com/WhatAmISupposedToPutHere/krun/blob/pipewire/crates/muvm/src/guest/bridge/common.rs#L745 After the fd is created, it is passed to a pipewire client running inside the vm, which in turn does a simple mmap() (with a non-zero offset) on the relevant fd. Not sure where exactly pipewire's code does that, the syscall was observed via stracing the relevant process.
