can we finally kill off CONFIG_FS_DAX_LIMITED

[Christoph Hellwig]

Hi all,

looking at the recent ZONE_DEVICE related changes we still have a
horrible maze of different code paths.  I already suggested to
depend on ARCH_HAS_PTE_SPECIAL for ZONE_DEVICE there, which all modern
architectures have anyway.  But the other odd special case is
CONFIG_FS_DAX_LIMITED which is just used for the xpram driver.  Does
this driver still see use?  If so can we make it behave like the
other DAX drivers and require a pgmap?  I think the biggest missing
part would be to implement ARCH_HAS_PTE_DEVMAP for s390.