2224  *                        a native SGL (NVMe PRP).
2233  * The native SGL is built starting in the first PRP
2237  * describe using the two PRP entriess inside the NVMe message, then PRP1
2238  * describes the first data memory segment, and PRP2 contains a pointer to a PRP
2240  * segments.  The PRP list will be contiguous.
2242  * The native SGL for NVMe devices is a Physical Region Page (PRP).  A PRP
2243  * consists of a list of PRP entries to describe a number of noncontigous
2247  * non-contiguous SGL into a PRP in this case.  All PRPs will describe
2250  * Each NVMe message contains two PRP entries.  The first (PRP1) either contains
2251  * a PRP list pointer or a PRP element, depending upon the command.  PRP2
2252  * contains the second PRP element if the memory being described fits within 2
2253  * PRP entries, or a PRP list pointer if the PRP spans more than two entries.
2255  * A PRP list pointer contains the address of a PRP list, structured as a linear
2256  * array of PRP entries.  Each PRP entry in this list describes a segment of
2259  * Each 64-bit PRP entry comprises an address and an offset field.  The address
2262  * first element in a PRP list may contain a non-zero offset, implying that all
2265  * Each PRP element normally describes 4KB of physical memory, with exceptions
2268  * first PRP element will contain a non-zero offset indicating where the region
2271  * described by the PRP list.
2273  * Since PRP entries lack any indication of size, the overall data buffer length
2275  * how many PRP entries are required to describe it.
2295 	 * without constructing any PRP.  in _base_build_nvme_prp()
2303 	 * For the PRP entries, use the specially allocated buffer of  in _base_build_nvme_prp()
2311 	 * want our first entry to be a PRP List entry.  in _base_build_nvme_prp()
2322 	 * Set PRP physical pointer, which initially points to the current PRP  in _base_build_nvme_prp()
2345 			 * This is the last entry in a PRP List, so we need to  in _base_build_nvme_prp()
2346 			 * put a PRP list pointer here.  What this does is:  in _base_build_nvme_prp()
2349 			 *   - set the PRP Entry to point to that page.  This  in _base_build_nvme_prp()
2350 			 *     is now the PRP List pointer.  in _base_build_nvme_prp()
2351 			 *   - bump the PRP Entry pointer the start of the  in _base_build_nvme_prp()
2352 			 *     next page.  Since all of this PRP memory is  in _base_build_nvme_prp()
2367 			 * Must fill in the first PRP pointer (PRP1) before  in _base_build_nvme_prp()
2373 			 * Now point to the second PRP entry within the  in _base_build_nvme_prp()
2379 			 * Should the PRP2 entry be a PRP List pointer or just  in _base_build_nvme_prp()
2380 			 * a regular PRP pointer?  If there is more than one  in _base_build_nvme_prp()
2381 			 * more page of data, must use a PRP List pointer.  in _base_build_nvme_prp()
2385 				 * PRP2 will contain a PRP List pointer because  in _base_build_nvme_prp()
2386 				 * more PRP's are needed with this command. The  in _base_build_nvme_prp()
2393 				 * The next PRP Entry will be the start of the  in _base_build_nvme_prp()
2394 				 * first PRP List.  in _base_build_nvme_prp()
2399 				 * After this, the PRP Entries are complete.  in _base_build_nvme_prp()
2400 				 * This command uses 2 PRP's and no PRP list.  in _base_build_nvme_prp()
2409 			 * all remaining PRP entries in a PRP List, one per  in _base_build_nvme_prp()
2462 	 * Nvme has a very convoluted prp format.  One prp is required  in base_make_prp_nvme()
2465 	 * boundary.  Driver also have to insert a PRP list pointer entry as  in base_make_prp_nvme()
2466 	 * the last entry in each physical page of the PRP list.  in base_make_prp_nvme()
2468 	 * NOTE: The first PRP "entry" is actually placed in the first  in base_make_prp_nvme()
2471 	 * of the PRP entries are built in the contiguous pcie buffer.  in base_make_prp_nvme()
2494 	 * For the PRP entries, use the specially allocated buffer of  in base_make_prp_nvme()
2508 	/* Build first prp, sge need not to be page aligned*/  in base_make_prp_nvme()
2534 		/* Put PRP pointer due to page boundary*/  in base_make_prp_nvme()
2629 	 * Build native NVMe PRP.  in _base_check_pcie_native_sgl()
6011 	    "Number of chains can fit in a PRP page(%d)\n",  in _base_allocate_pcie_sgl_pool()
6590 	 * ((sg_tablesize * 8) - 1) is the max PRP's minus the first PRP entry  in _base_allocate_memory_pools()
6591 	 * that is placed in the main message frame.  8 is the size of each PRP  in _base_allocate_memory_pools()
6592 	 * entry or PRP list pointer entry.  8 is subtracted from page_size  in _base_allocate_memory_pools()
6593 	 * because of the PRP list pointer entry at the end of a page, so this  in _base_allocate_memory_pools()
6594 	 * is not counted as a PRP entry.  The 1 added page is a round up.  in _base_allocate_memory_pools()
6597 	 * be required for NVMe PRP's, only each set of NVMe blocks will be  in _base_allocate_memory_pools()