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original_kernel/arch/alpha/include/asm/sparsemem.h

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alpha: switch from DISCONTIGMEM to SPARSEMEM Patch series "arch, mm: deprecate DISCONTIGMEM", v2. It's been a while since DISCONTIGMEM is generally considered deprecated, but it is still used by four architectures. This set replaces DISCONTIGMEM with a different way to handle holes in the memory map and marks DISCONTIGMEM configuration as BROKEN in Kconfigs of these architectures with the intention to completely remove it in several releases. While for 64-bit alpha and ia64 the switch to SPARSEMEM is quite obvious and was a matter of moving some bits around, for smaller 32-bit arc and m68k SPARSEMEM is not necessarily the best thing to do. On 32-bit machines SPARSEMEM would require large sections to make section index fit in the page flags, but larger sections mean that more memory is wasted for unused memory map. Besides, pfn_to_page() and page_to_pfn() become less efficient, at least on arc. So I've decided to generalize arm's approach for freeing of unused parts of the memory map with FLATMEM and enable it for both arc and m68k. The details are in the description of patches 10 (arc) and 13 (m68k). This patch (of 13): Enable SPARSEMEM support on alpha and deprecate DISCONTIGMEM. The required changes are mostly around moving duplicated definitions of page access and address conversion macros to a common place and making sure they are available for all memory models. The DISCONTINGMEM support is marked as BROKEN an will be removed in a couple of releases. Link: https://lkml.kernel.org/r/20201101170454.9567-1-rppt@kernel.org Link: https://lkml.kernel.org/r/20201101170454.9567-2-rppt@kernel.org Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Greg Ungerer <gerg@linux-m68k.org> Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matt Turner <mattst88@gmail.com> Cc: Meelis Roos <mroos@linux.ee> Cc: Michael Schmitz <schmitzmic@gmail.com> Cc: Russell King <linux@armlinux.org.uk> Cc: Tony Luck <tony.luck@intel.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-12-15 11:09:28 +08:00
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_ALPHA_SPARSEMEM_H
#define _ASM_ALPHA_SPARSEMEM_H
#ifdef CONFIG_SPARSEMEM
#define SECTION_SIZE_BITS 27
/*
* According to "Alpha Architecture Reference Manual" physical
* addresses are at most 48 bits.
* https://download.majix.org/dec/alpha_arch_ref.pdf
*/
#define MAX_PHYSMEM_BITS 48
#endif /* CONFIG_SPARSEMEM */
#endif /* _ASM_ALPHA_SPARSEMEM_H */