On Tue, Sep 26, 2023 at 7:49 PM Michael S. Tsirkin <mst@xxxxxxxxxx> wrote: > > On Tue, Sep 26, 2023 at 10:32:39AM +0800, Jason Wang wrote: > > It's the implementation details in legacy. The device needs to make > > sure (reset) the driver can work (is done before get_status return). > > I think that there's no way to make it reliably work for all legacy drivers. Yes, we may have ancient drivers. > > They just assumed a software backend and did not bother with DMA > ordering. You can try to avoid resets, they are not that common so > things will tend to mostly work if you don't stress them to much with > things like hot plug/unplug in a loop. Or you can try to use a driver > after 2011 which is more aware of hardware ordering and flushes the > reset write with a read. One of these two tricks, I think, is the magic > behind the device exposing memory bar 0 that you mention. Right this is what I see for hardware legacy devices shipped by some cloud vendors. Thanks > > -- > MST >
