> From: Jason Gunthorpe <jgg@xxxxxxxxxx> > Sent: Wednesday, October 11, 2023 8:00 PM > > On Wed, Oct 11, 2023 at 02:00:30AM +0000, Tian, Kevin wrote: > > > From: Jason Gunthorpe <jgg@xxxxxxxxxx> > > > Sent: Tuesday, October 10, 2023 7:34 PM > > > > > > On Tue, Oct 10, 2023 at 08:42:13AM +0000, Tian, Kevin wrote: > > > > > From: ankita@xxxxxxxxxx <ankita@xxxxxxxxxx> > > > > > Sent: Sunday, October 8, 2023 4:23 AM > > > > > > > > > > PCI BAR are aligned to the power-of-2, but the actual memory on the > > > > > device may not. A read or write access to the physical address from > the > > > > > last device PFN up to the next power-of-2 aligned physical address > > > > > results in reading ~0 and dropped writes. > > > > > > > > > > > > > my question to v10 was not answered. posted again: > > > > > > The device FW knows and tells the VM. > > > > > > > This driver reads the size info from ACPI and records it as > > nvdev->memlength. > > Yes, the ACPI tables have a copy of the size. So the ACPI copy is mainly introduced for the use of VFIO given the real device driver can already retrieve it from device FW? > > > But nvdev->memlength is not exposed to the userspace. How does the > virtual > > FW acquires this knowledge and then report it to the VM? > > It isn't virtual FW, I said device FW. The device itself knows how it > is configured and it can report details about the the memory > space. The VM just DMA's a RPC and asks it. > Interesting. Perhaps this message should be included in the commit message to help compose a clear picture. With that, Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
