• Dan Williams's avatar
    libnvdimm, nfit: handle unarmed dimms, mark namespaces read-only · 58138820
    Dan Williams authored
    Upon detection of an unarmed dimm in a region, arrange for descendant
    BTT, PMEM, or BLK instances to be read-only.  A dimm is primarily marked
    "unarmed" via flags passed by platform firmware (NFIT).
    
    The flags in the NFIT memory device sub-structure indicate the state of
    the data on the nvdimm relative to its energy source or last "flush to
    persistence".  For the most part there is nothing the driver can do but
    advertise the state of these flags in sysfs and emit a message if
    firmware indicates that the contents of the device may be corrupted.
    However, for the case of ACPI_NFIT_MEM_ARMED, the driver can arrange for
    the block devices incorporating that nvdimm to be marked read-only.
    This is a safe default as the data is still available and new writes are
    held off until the administrator either forces read-write mode, or the
    energy source becomes armed.
    
    A 'read_only' attribute is added to REGION devices to allow for
    overriding the default read-only policy of all descendant block devices.
    Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
    58138820
nfit.c 41.7 KB