6c359eb1dc
On systems where physical memory begins at a non-zero address, defining PHYS_OFFSET (which influences ARCH_PFN_OFFSET) can save us time & memory by avoiding book-keeping for pages from address zero to the start of memory. Some MIPS platforms already make use of this, but with the definition of PHYS_OFFSET being compile-time constant it hasn't been possible to enable this optimization for a kernel which may run on systems with varying physical memory base addresses. Introduce a new Kconfig option CONFIG_MIPS_AUTO_PFN_OFFSET which, when enabled, makes ARCH_PFN_OFFSET a variable & detects it from the boot memory map (which for example may have been populated from DT). The relationship with PHYS_OFFSET is reversed, with PHYS_OFFSET now being based on ARCH_PFN_OFFSET. This is because ARCH_PFN_OFFSET is used far more often, so avoiding the need for runtime calculation gives us a smaller impact on kernel text size (0.1% rather than 0.15% for 64r6el_defconfig). Signed-off-by: Paul Burton <paul.burton@mips.com> Suggested-by: Vladimir Kondratiev <vladimir.kondratiev@intel.com> Patchwork: https://patchwork.linux-mips.org/patch/20048/ Cc: James Hogan <jhogan@kernel.org> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: linux-mips@linux-mips.org |
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| .. | ||
| cpu-feature-overrides.h | ||
| floppy.h | ||
| ide.h | ||
| ioremap.h | ||
| irq.h | ||
| kernel-entry-init.h | ||
| kmalloc.h | ||
| mangle-port.h | ||
| mc146818rtc.h | ||
| spaces.h | ||
| topology.h | ||
| war.h | ||