On Thu, Sep 27, 2018 at 11:05:13PM +0800, Zihan Yang wrote:
Laszlo Ersek lersek@redhat.com 于2018年9月26日周三 上午1:17写道：
First, I fail to see the use case where ~256 PCI bus numbers aren't enough. If I strain myself, perhaps I can imagine using ~200 PCIe root ports on Q35 (each of which requires a separate bus number), so that we can independently hot-plug 200 devices then. And that's supposedly not enough, because we want... 300? 400? A thousand? Doesn't sound realistic to me. (This is not meant to be a strawman argument, I really have no idea what the feature would be useful for.)
It might not be very intuitive, but it indeed exists. The very beginning discussion about 4 months ago has mentioned a possible use case, and I paste it here
[...]
Things might change in the future if we can figure out a better solution, and I hope we can have an easier and more elegant solution in OVMF. But now we are just trying to give a possible solution as a poc.
Thanks. I wasn't aware this was a proof of concept. (Nor have I been following the discussions on the qemu list.) I don't think it makes sense to merge this into the main SeaBIOS repository. The QEMU/firmware interface is already complex and I don't think we should complicate it further without a more concrete use case. In particular, it seems unclear if 256 buses is enough or if 1024 buses is too little.
-Kevin