On Tue, Jul 29, 2025 at 09:52:09AM +0200, Christoph Hellwig wrote: > On Sun, Jul 27, 2025 at 03:51:58PM -0300, Jason Gunthorpe wrote: > > On Thu, Jul 24, 2025 at 09:59:22AM +0200, Christoph Hellwig wrote: > > > On Thu, Jul 24, 2025 at 10:55:33AM +0300, Leon Romanovsky wrote: > > > > Please, see last patch in the series > > > > https://lore.kernel.org/all/aea452cc27ca9e5169f7279d7b524190c39e7260.1753274085.git.leo...@nvidia.com > > > > It gives me a way to call p2p code with stable pointer for whole BAR. > > > > > > > > > > That simply can't work. > > > > Why not? > > > > That's the whole point of this, to remove struct page and use > > something else as a handle for the p2p when doing the DMA API stuff. > > Because the struct page is the only thing that: > > a) dma-mapping works on > b) is the only place we can discover the routing information, but also > more importantly ensure that the underlying page is still present > and the device is not hot unplugged, or in a very theoretical worst > case replaced by something else.
It is correct in general case, but here we are talking about MMIO memory, which is "connected" to device X and routing information is stable. Thanks > >
