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The PAPR based virtualized persistent memory devices are only supported on POWER9 and above. In the followup patch, the kernel will switch the persistent memory cache flush functions to use a new `dcbf` variant instruction. The new instructions even though added in ISA 3.1 works even on P8 and P9 because these are implemented as a variant of existing `dcbf` and `hwsync` and on P8 and P9 behaves as such. Considering these devices are only supported on P8 and above, update the driver to prevent a P7-compat guest from using persistent memory devices. We don't update of_pmem driver with the same condition, because, on bare-metal, the firmware enables pmem support only on P9 and above. There the kernel depends on OPAL firmware to restrict exposing persistent memory related device tree entries on older hardware. of_pmem.ko is written without any arch dependency and we don't want to add ppc64 specific cpu feature check in of_pmem driver. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200701072235.223558-2-aneesh.kumar@linux.ibm.com
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.