• Dan Williams's avatar
    libnvdimm, e820: make CONFIG_X86_PMEM_LEGACY a tristate option · 7a67832c
    Dan Williams authored
    We currently register a platform device for e820 type-12 memory and
    register a nvdimm bus beneath it.  Registering the platform device
    triggers the device-core machinery to probe for a driver, but that
    search currently comes up empty.  Building the nvdimm-bus registration
    into the e820_pmem platform device registration in this way forces
    libnvdimm to be built-in.  Instead, convert the built-in portion of
    CONFIG_X86_PMEM_LEGACY to simply register a platform device and move the
    rest of the logic to the driver for e820_pmem, for the following
    reasons:
    
    1/ Letting e820_pmem support be a module allows building and testing
       libnvdimm.ko changes without rebooting
    
    2/ All the normal policy around modules can be applied to e820_pmem
       (unbind to disable and/or blacklisting the module from loading by
       default)
    
    3/ Moving the driver to a generic location and converting it to scan
       "iomem_resource" rather than "e820.map" means any other architecture can
       take advantage of this simple nvdimm resource discovery mechanism by
       registering a resource named "Persistent Memory (legacy)"
    
    Cc: Christoph Hellwig <hch@lst.de>
    Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
    7a67832c
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