/INVALID_PFN [=option]

    The /INVALID_PFN qualifier, which is valid only on platforms that
    supply an I/O memory map, causes SDA to display only page table
    entries that map to PFNs that are not in the system's private
    memory or in Galaxy-shared memory, and which are not I/O access
    pages.

    /INVALID_PFN has two optional keywords, READONLY and WRITABLE. If
    neither keyword is specified, all relevant pages are displayed.

    If READONLY is specified, only pages marked for no write
    access are displayed. If WRITABLE is specified, only pages
    that allow write access are displayed. For example, SHOW PAGE_
    TABLE/ALL/INVALID_PFN=WRITABLE would display all system pages
    whose protection allows write, but which map to PFNs that do not
    belong to this system.