Dan Williams <dan.j.willi...@intel.com> writes: > On Sat, Nov 16, 2019 at 4:15 AM Aneesh Kumar K.V > <aneesh.ku...@linux.ibm.com> wrote: >>
.... >> >> Considering the direct-map map size is not going to be user selectable, >> do you agree that we can skip the above step 0 configuration you >> suggested. >> >> The changes proposed in the patch series essentially does the rest. >> >> 1) It validate the size against the arch specific limit during >> namespace creation. (part of step 1) > > This validation is a surprise failure to ndctl. > >> 2) It also disable initializing a region if it find the size not >> correctly aligned as per the platform requirement. > > There needs to be a way for the user to discover the correct alignment > that the kernel will accept. > >> 3) Direct map mapping size is different from supported_alignment for a >> namespace. The supported alignment controls what possible PAGE SIZE user >> want the >> namespace to be mapped to user space. > > No, the namespace alignment is different than the page mapping size. > The alignment is only interpreted as a mapping size at the device-dax > level, otherwise at the raw namespace level it's just an arbitrary > alignment. > >> With the above do you think the current patch series is good? > > I don't think we've quite converged on a solution. How about we make it a property of seed device. ie, we add `supported_size_align` RO attribute to the seed device. ndctl can use this to validate the size value. So this now becomes step0 sys/bus/nd/devices/region0> cat btt0.0/supported_size_align 16777216 /sys/bus/nd/devices/region0> cat pfn0.0/supported_size_align 16777216 /sys/bus/nd/devices/region0> cat dax0.0/supported_size_align 16777216 /sys/bus/nd/devices/region0> We follow that up with validating the size value written to size attribute(step 1). While initializing the namespaces already present in a region we again validate the size and if not properly aligned we mark the region disabled. -aneesh
