Re: failure to setup devdax over fake nvdimm

Le 16/03/2019 à 00:12, Dan Williams a écrit : > On Fri, Mar 15, 2019 at 3:31 PM Brice Goglin <Brice.Goglin(a)inria.fr&gt; wrote: >> Hello Dan, >> >> On a machine emulating nvdimms over DDR using the memmap kernel parameter, >> I can't enable devdax anymore with ndctl, when using your libnvdimm-pending >> branch (1ffc664f9b8ca7346f2af0fb4f62b923193bf65c): >> >> # ndctl create-namespace -f -e namespace1.0 -t pmem -m devdax >> libndctl: ndctl_dax_enable: dax1.0: failed to enable >> Error: namespace1.0: failed to enable >> failed to reconfigure namespace: No such device or address >> >> In the previous version of your libnvdimm-pending branch that I used before >> (8d4a7e3da68e88a6efd3acb5cc971d0c2ca219a4 from January 8th) this ndctl line >> worked fine right after boot. >> >> The difference between strace ndctl doesn't show anything obvious. >> * /sys/devices/platform/e820_pmem/ndbus0/region1/namespace1.0/holder_class contains nothing instead of "dax" >> * /sys/devices/platform/e820_pmem/ndbus0/region1/dax_seed contains dax1.0 instead of dax1.1 >> >> Any idea where to look? > If my libnvdimm-pending branch worked it is likely due to the > alignment padding fixes I had pending there. Can you post the dmesg > from this failure? > > The alignment padding fixes are being abandoned in favor of just > teaching the core-mm to not require section (128MB) alignment, but > until then you need to make sure your persistent memory is 128MB > aligned. I am passing memmap=24G!7G memmap=24G!39G to the kernel command-line. It looks properly aligned. dmesg is below. Nothing appears when ndctl fails.