On Tue, Nov 08, 2022 at 04:17:06PM +0000, Luck, Tony wrote: > > If it is feasible in future that hardware vendors can make patrol > > scrubber programmable, we can even direct the scanning to patrol > > scrubber. > > There was an attempt to create an ACPI interface for this. I don't know if it made > it into the standard. I briefly checked the latest ACPI spec, and it seems that some interfaces to control (h/w based) patrol scrubbing are defined. https://uefi.org/specs/ACPI/6.5/05_ACPI_Software_Programming_Model.html#acpi-ras-feature-table-rasf > I didn't do anything with it for Linux because the interface was > quite complex. > > From a h/w perspective it might always be complex. Consecutive system physical > addresses are generally interleaved across multiple memory controllers, channels, > DIMMs and ranks. While patrol scrubbing may be done by each memory controller > at the channel level. > > So a simple request to scan a few megabytes of system physical address would > require address translation to figure out the channel addresses on each of the > memory controllers and programming each to scan the pieces they contribute to > the target range. I expect that the physical address visible to the kernel is transparently translated to the real address in which DIMM in which channel. - Naoya Horiguchi
