Hi Peter, On Sun, Aug 30, 2026 at 11:41:48AM +0100, Peter Robinson wrote: > Hi Kuan-Wei, > > > Add 9P network filesystem support to U-Boot. > > > > It allows U-Boot to directly mount host directories in virtualization > > environments via virtio. > > It would be useful to give an overview in the cover letter how/where > you expect to be used. While new features are always welcome they also > come with a maintenance burden so some background is always useful to > provide more information.
The use case is loading images directly from the host into the VM. That way I don't need to rebuild and repack disk images like ext4 every time I modify the kernel, and I also don't have to bother setting up a TFTP server. I got the idea a while ago while browsing the upstream LK code and noticed it had 9P support. I thought it would be cool to have something similar in U-Boot for kernel loading and testing in qemu. I will add this background to the cover letter if a v3 is needed. > > From a network stack PoV does this work, been tested, with both the > legacy stack and LWIP stack? I would tend to push this towards working > with the LWIP stack as we're moving towards that being the default for > standard U-Boot (not in SPL) and I wouldn't expect 9P to be supported > in SPL. > I have only implemented and tested 9P over virtio, so it uses virtqueues and doesn't go through the network stack at all. It's independent of both legacy and LWIP stacks. I am not sure if anyone would actually want 9P over TCP in U-Boot, but if there is demand for it, I can look into adding a transport driver over the network stack. Regards, Kuan-Wei
