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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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26f9d5fd82
Initial HIGHMEM support on ARC was introduced for PAE40 where the low
memory (0x8000_0000 based) and high memory (0x1_0000_0000) were
physically contiguous. So CONFIG_FLATMEM sufficed (despite a peipheral
hole in the middle, which wasted a bit of struct page memory, but things
worked).
However w/o PAE, highmem was not possible and we could only reach
~1.75GB of DDR. Now there is a use case to access ~4GB of DDR w/o PAE40
The idea is to have low memory at canonical 0x8000_0000 and highmem
at 0 so enire 4GB address space is available for physical addressing
This needs additional platform/interconnect mapping to convert
the non contiguous physical addresses into linear bus adresses.
From Linux point of view, non contiguous divide means FLATMEM no
longer works and DISCONTIGMEM is needed to track the pfns in the 2
regions.
This scheme would also work for PAE40, only better in that we don't
waste struct page memory for the peripheral hole.
The DT description will be something like
memory {
...
reg = <0x80000000 0x200000000 /* 512MB: lowmem */
0x00000000 0x10000000>; /* 256MB: highmem */
}
Signed-off-by: Noam Camus <noamc@ezchip.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
234 lines
6.1 KiB
C
234 lines
6.1 KiB
C
/*
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* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/bootmem.h>
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#include <linux/memblock.h>
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#ifdef CONFIG_BLK_DEV_INITRD
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#include <linux/initrd.h>
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#endif
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#include <linux/of_fdt.h>
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#include <linux/swap.h>
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#include <linux/module.h>
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#include <linux/highmem.h>
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#include <asm/page.h>
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#include <asm/pgalloc.h>
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#include <asm/sections.h>
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#include <asm/arcregs.h>
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pgd_t swapper_pg_dir[PTRS_PER_PGD] __aligned(PAGE_SIZE);
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char empty_zero_page[PAGE_SIZE] __aligned(PAGE_SIZE);
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EXPORT_SYMBOL(empty_zero_page);
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static const unsigned long low_mem_start = CONFIG_LINUX_LINK_BASE;
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static unsigned long low_mem_sz;
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#ifdef CONFIG_HIGHMEM
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static unsigned long min_high_pfn, max_high_pfn;
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static u64 high_mem_start;
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static u64 high_mem_sz;
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#endif
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#ifdef CONFIG_DISCONTIGMEM
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struct pglist_data node_data[MAX_NUMNODES] __read_mostly;
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EXPORT_SYMBOL(node_data);
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#endif
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/* User can over-ride above with "mem=nnn[KkMm]" in cmdline */
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static int __init setup_mem_sz(char *str)
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{
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low_mem_sz = memparse(str, NULL) & PAGE_MASK;
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/* early console might not be setup yet - it will show up later */
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pr_info("\"mem=%s\": mem sz set to %ldM\n", str, TO_MB(low_mem_sz));
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return 0;
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}
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early_param("mem", setup_mem_sz);
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void __init early_init_dt_add_memory_arch(u64 base, u64 size)
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{
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int in_use = 0;
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if (!low_mem_sz) {
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if (base != low_mem_start)
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panic("CONFIG_LINUX_LINK_BASE != DT memory { }");
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low_mem_sz = size;
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in_use = 1;
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} else {
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#ifdef CONFIG_HIGHMEM
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high_mem_start = base;
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high_mem_sz = size;
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in_use = 1;
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#endif
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}
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pr_info("Memory @ %llx [%lldM] %s\n",
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base, TO_MB(size), !in_use ? "Not used":"");
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}
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#ifdef CONFIG_BLK_DEV_INITRD
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static int __init early_initrd(char *p)
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{
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unsigned long start, size;
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char *endp;
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start = memparse(p, &endp);
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if (*endp == ',') {
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size = memparse(endp + 1, NULL);
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initrd_start = (unsigned long)__va(start);
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initrd_end = (unsigned long)__va(start + size);
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}
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return 0;
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}
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early_param("initrd", early_initrd);
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#endif
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/*
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* First memory setup routine called from setup_arch()
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* 1. setup swapper's mm @init_mm
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* 2. Count the pages we have and setup bootmem allocator
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* 3. zone setup
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*/
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void __init setup_arch_memory(void)
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{
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unsigned long zones_size[MAX_NR_ZONES];
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unsigned long zones_holes[MAX_NR_ZONES];
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init_mm.start_code = (unsigned long)_text;
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init_mm.end_code = (unsigned long)_etext;
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init_mm.end_data = (unsigned long)_edata;
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init_mm.brk = (unsigned long)_end;
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/* first page of system - kernel .vector starts here */
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min_low_pfn = ARCH_PFN_OFFSET;
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/* Last usable page of low mem */
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max_low_pfn = max_pfn = PFN_DOWN(low_mem_start + low_mem_sz);
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#ifdef CONFIG_FLATMEM
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/* pfn_valid() uses this */
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max_mapnr = max_low_pfn - min_low_pfn;
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#endif
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/*------------- bootmem allocator setup -----------------------*/
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/*
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* seed the bootmem allocator after any DT memory node parsing or
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* "mem=xxx" cmdline overrides have potentially updated @arc_mem_sz
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*
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* Only low mem is added, otherwise we have crashes when allocating
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* mem_map[] itself. NO_BOOTMEM allocates mem_map[] at the end of
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* avail memory, ending in highmem with a > 32-bit address. However
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* it then tries to memset it with a truncaed 32-bit handle, causing
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* the crash
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*/
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memblock_add_node(low_mem_start, low_mem_sz, 0);
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memblock_reserve(low_mem_start, __pa(_end) - low_mem_start);
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#ifdef CONFIG_BLK_DEV_INITRD
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if (initrd_start)
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memblock_reserve(__pa(initrd_start), initrd_end - initrd_start);
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#endif
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early_init_fdt_reserve_self();
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early_init_fdt_scan_reserved_mem();
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memblock_dump_all();
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/*----------------- node/zones setup --------------------------*/
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memset(zones_size, 0, sizeof(zones_size));
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memset(zones_holes, 0, sizeof(zones_holes));
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zones_size[ZONE_NORMAL] = max_low_pfn - min_low_pfn;
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zones_holes[ZONE_NORMAL] = 0;
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/*
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* We can't use the helper free_area_init(zones[]) because it uses
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* PAGE_OFFSET to compute the @min_low_pfn which would be wrong
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* when our kernel doesn't start at PAGE_OFFSET, i.e.
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* PAGE_OFFSET != CONFIG_LINUX_LINK_BASE
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*/
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free_area_init_node(0, /* node-id */
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zones_size, /* num pages per zone */
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min_low_pfn, /* first pfn of node */
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zones_holes); /* holes */
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#ifdef CONFIG_HIGHMEM
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/*
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* Populate a new node with highmem
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*
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* On ARC (w/o PAE) HIGHMEM addresses are actually smaller (0 based)
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* than addresses in normal ala low memory (0x8000_0000 based).
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* Even with PAE, the huge peripheral space hole would waste a lot of
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* mem with single mem_map[]. This warrants a mem_map per region design.
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* Thus HIGHMEM on ARC is imlemented with DISCONTIGMEM.
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*
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* DISCONTIGMEM in turns requires multiple nodes. node 0 above is
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* populated with normal memory zone while node 1 only has highmem
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*/
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node_set_online(1);
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min_high_pfn = PFN_DOWN(high_mem_start);
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max_high_pfn = PFN_DOWN(high_mem_start + high_mem_sz);
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zones_size[ZONE_NORMAL] = 0;
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zones_holes[ZONE_NORMAL] = 0;
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zones_size[ZONE_HIGHMEM] = max_high_pfn - min_high_pfn;
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zones_holes[ZONE_HIGHMEM] = 0;
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free_area_init_node(1, /* node-id */
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zones_size, /* num pages per zone */
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min_high_pfn, /* first pfn of node */
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zones_holes); /* holes */
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high_memory = (void *)(min_high_pfn << PAGE_SHIFT);
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kmap_init();
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#endif
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}
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/*
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* mem_init - initializes memory
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*
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* Frees up bootmem
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* Calculates and displays memory available/used
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*/
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void __init mem_init(void)
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{
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#ifdef CONFIG_HIGHMEM
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unsigned long tmp;
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reset_all_zones_managed_pages();
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for (tmp = min_high_pfn; tmp < max_high_pfn; tmp++)
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free_highmem_page(pfn_to_page(tmp));
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#endif
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free_all_bootmem();
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mem_init_print_info(NULL);
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}
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/*
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* free_initmem: Free all the __init memory.
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*/
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void __init_refok free_initmem(void)
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{
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free_initmem_default(-1);
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}
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#ifdef CONFIG_BLK_DEV_INITRD
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void __init free_initrd_mem(unsigned long start, unsigned long end)
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{
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free_reserved_area((void *)start, (void *)end, -1, "initrd");
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}
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#endif
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