368ff8f14d
We find the runtime address of _stext and relocate ourselves based
on the following calculation.
virtual_base = ALIGN(KERNELBASE,KERNEL_TLB_PIN_SIZE) +
MODULO(_stext.run,KERNEL_TLB_PIN_SIZE)
relocate() is called with the Effective Virtual Base Address (as
shown below)
| Phys. Addr| Virt. Addr |
Page |------------------------|
Boundary | | |
| | |
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Kernel Load |___________|_ __ _ _ _ _|<- Effective
Addr(_stext)| | ^ |Virt. Base Addr
| | | |
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| |reloc_offset|
| | | |
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| |______v_____|<-(KERNELBASE)%TLB_SIZE
| | |
| | |
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Page |-----------|------------|
Boundary | | |
On BookE, we need __va() & __pa() early in the boot process to access
the device tree.
Currently this has been defined as :
#define __va(x) ((void *)(unsigned long)((phys_addr_t)(x) -
PHYSICAL_START + KERNELBASE)
where:
PHYSICAL_START is kernstart_addr - a variable updated at runtime.
KERNELBASE is the compile time Virtual base address of kernel.
This won't work for us, as kernstart_addr is dynamic and will yield different
results for __va()/__pa() for same mapping.
e.g.,
Let the kernel be loaded at 64MB and KERNELBASE be 0xc0000000 (same as
PAGE_OFFSET).
In this case, we would be mapping 0 to 0xc0000000, and kernstart_addr = 64M
Now __va(1MB) = (0x100000) - (0x4000000) + 0xc0000000
= 0xbc100000 , which is wrong.
it should be : 0xc0000000 + 0x100000 = 0xc0100000
On platforms which support AMP, like PPC_47x (based on 44x), the kernel
could be loaded at highmem. Hence we cannot always depend on the compile
time constants for mapping.
Here are the possible solutions:
1) Update kernstart_addr(PHSYICAL_START) to match the Physical address of
compile time KERNELBASE value, instead of the actual Physical_Address(_stext).
The disadvantage is that we may break other users of PHYSICAL_START. They
could be replaced with __pa(_stext).
2) Redefine __va() & __pa() with relocation offset
#ifdef CONFIG_RELOCATABLE_PPC32
#define __va(x) ((void *)(unsigned long)((phys_addr_t)(x) - PHYSICAL_START + (KERNELBASE + RELOC_OFFSET)))
#define __pa(x) ((unsigned long)(x) + PHYSICAL_START - (KERNELBASE + RELOC_OFFSET))
#endif
where, RELOC_OFFSET could be
a) A variable, say relocation_offset (like kernstart_addr), updated
at boot time. This impacts performance, as we have to load an additional
variable from memory.
OR
b) #define RELOC_OFFSET ((PHYSICAL_START & PPC_PIN_SIZE_OFFSET_MASK) - \
(KERNELBASE & PPC_PIN_SIZE_OFFSET_MASK))
This introduces more calculations for doing the translation.
3) Redefine __va() & __pa() with a new variable
i.e,
#define __va(x) ((void *)(unsigned long)((phys_addr_t)(x) + VIRT_PHYS_OFFSET))
where VIRT_PHYS_OFFSET :
#ifdef CONFIG_RELOCATABLE_PPC32
#define VIRT_PHYS_OFFSET virt_phys_offset
#else
#define VIRT_PHYS_OFFSET (KERNELBASE - PHYSICAL_START)
#endif /* CONFIG_RELOCATABLE_PPC32 */
where virt_phy_offset is updated at runtime to :
Effective KERNELBASE - kernstart_addr.
Taking our example, above:
virt_phys_offset = effective_kernelstart_vaddr - kernstart_addr
= 0xc0400000 - 0x400000
= 0xc0000000
and
__va(0x100000) = 0xc0000000 + 0x100000 = 0xc0100000
which is what we want.
I have implemented (3) in the following patch which has same cost of
operation as the existing one.
I have tested the patches on 440x platforms only. However this should
work fine for PPC_47x also, as we only depend on the runtime address
and the current TLB XLAT entry for the startup code, which is available
in r25. I don't have access to a 47x board yet. So, it would be great if
somebody could test this on 47x.
Signed-off-by: Suzuki K. Poulose <suzuki@in.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Kumar Gala <galak@kernel.crashing.org>
Cc: linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
Signed-off-by: Josh Boyer <jwboyer@gmail.com>
223 lines
5.6 KiB
C
223 lines
5.6 KiB
C
/*
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* PowerPC version
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* Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
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*
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* Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
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* and Cort Dougan (PReP) (cort@cs.nmt.edu)
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* Copyright (C) 1996 Paul Mackerras
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* PPC44x/36-bit changes by Matt Porter (mporter@mvista.com)
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*
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* Derived from "arch/i386/mm/init.c"
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* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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*/
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#include <linux/module.h>
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#include <linux/sched.h>
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/string.h>
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#include <linux/types.h>
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#include <linux/mm.h>
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#include <linux/stddef.h>
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#include <linux/init.h>
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#include <linux/bootmem.h>
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#include <linux/highmem.h>
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#include <linux/initrd.h>
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#include <linux/pagemap.h>
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#include <linux/memblock.h>
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#include <linux/gfp.h>
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#include <linux/slab.h>
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#include <linux/hugetlb.h>
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#include <asm/pgalloc.h>
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#include <asm/prom.h>
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#include <asm/io.h>
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#include <asm/pgtable.h>
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#include <asm/mmu.h>
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#include <asm/smp.h>
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#include <asm/machdep.h>
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#include <asm/btext.h>
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#include <asm/tlb.h>
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#include <asm/sections.h>
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#include <asm/system.h>
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#include <asm/hugetlb.h>
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#include "mmu_decl.h"
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#if defined(CONFIG_KERNEL_START_BOOL) || defined(CONFIG_LOWMEM_SIZE_BOOL)
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/* The amount of lowmem must be within 0xF0000000 - KERNELBASE. */
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#if (CONFIG_LOWMEM_SIZE > (0xF0000000 - PAGE_OFFSET))
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#error "You must adjust CONFIG_LOWMEM_SIZE or CONFIG_START_KERNEL"
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#endif
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#endif
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#define MAX_LOW_MEM CONFIG_LOWMEM_SIZE
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phys_addr_t total_memory;
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phys_addr_t total_lowmem;
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phys_addr_t memstart_addr = (phys_addr_t)~0ull;
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EXPORT_SYMBOL(memstart_addr);
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phys_addr_t kernstart_addr;
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EXPORT_SYMBOL(kernstart_addr);
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#ifdef CONFIG_RELOCATABLE_PPC32
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/* Used in __va()/__pa() */
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long long virt_phys_offset;
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EXPORT_SYMBOL(virt_phys_offset);
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#endif
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phys_addr_t lowmem_end_addr;
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int boot_mapsize;
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#ifdef CONFIG_PPC_PMAC
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unsigned long agp_special_page;
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EXPORT_SYMBOL(agp_special_page);
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#endif
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void MMU_init(void);
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/* XXX should be in current.h -- paulus */
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extern struct task_struct *current_set[NR_CPUS];
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/*
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* this tells the system to map all of ram with the segregs
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* (i.e. page tables) instead of the bats.
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* -- Cort
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*/
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int __map_without_bats;
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int __map_without_ltlbs;
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/*
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* This tells the system to allow ioremapping memory marked as reserved.
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*/
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int __allow_ioremap_reserved;
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/* max amount of low RAM to map in */
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unsigned long __max_low_memory = MAX_LOW_MEM;
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/*
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* Check for command-line options that affect what MMU_init will do.
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*/
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void MMU_setup(void)
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{
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/* Check for nobats option (used in mapin_ram). */
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if (strstr(cmd_line, "nobats")) {
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__map_without_bats = 1;
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}
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if (strstr(cmd_line, "noltlbs")) {
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__map_without_ltlbs = 1;
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}
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#ifdef CONFIG_DEBUG_PAGEALLOC
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__map_without_bats = 1;
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__map_without_ltlbs = 1;
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#endif
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}
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/*
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* MMU_init sets up the basic memory mappings for the kernel,
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* including both RAM and possibly some I/O regions,
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* and sets up the page tables and the MMU hardware ready to go.
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*/
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void __init MMU_init(void)
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{
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if (ppc_md.progress)
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ppc_md.progress("MMU:enter", 0x111);
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/* parse args from command line */
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MMU_setup();
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/*
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* Reserve gigantic pages for hugetlb. This MUST occur before
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* lowmem_end_addr is initialized below.
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*/
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reserve_hugetlb_gpages();
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if (memblock.memory.cnt > 1) {
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#ifndef CONFIG_WII
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memblock.memory.cnt = 1;
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memblock_analyze();
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printk(KERN_WARNING "Only using first contiguous memory region");
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#else
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wii_memory_fixups();
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#endif
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}
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total_lowmem = total_memory = memblock_end_of_DRAM() - memstart_addr;
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lowmem_end_addr = memstart_addr + total_lowmem;
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#ifdef CONFIG_FSL_BOOKE
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/* Freescale Book-E parts expect lowmem to be mapped by fixed TLB
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* entries, so we need to adjust lowmem to match the amount we can map
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* in the fixed entries */
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adjust_total_lowmem();
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#endif /* CONFIG_FSL_BOOKE */
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if (total_lowmem > __max_low_memory) {
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total_lowmem = __max_low_memory;
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lowmem_end_addr = memstart_addr + total_lowmem;
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#ifndef CONFIG_HIGHMEM
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total_memory = total_lowmem;
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memblock_enforce_memory_limit(total_lowmem);
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memblock_analyze();
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#endif /* CONFIG_HIGHMEM */
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}
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/* Initialize the MMU hardware */
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if (ppc_md.progress)
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ppc_md.progress("MMU:hw init", 0x300);
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MMU_init_hw();
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/* Map in all of RAM starting at KERNELBASE */
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if (ppc_md.progress)
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ppc_md.progress("MMU:mapin", 0x301);
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mapin_ram();
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/* Initialize early top-down ioremap allocator */
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ioremap_bot = IOREMAP_TOP;
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/* Map in I/O resources */
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if (ppc_md.progress)
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ppc_md.progress("MMU:setio", 0x302);
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if (ppc_md.progress)
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ppc_md.progress("MMU:exit", 0x211);
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/* From now on, btext is no longer BAT mapped if it was at all */
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#ifdef CONFIG_BOOTX_TEXT
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btext_unmap();
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#endif
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/* Shortly after that, the entire linear mapping will be available */
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memblock_set_current_limit(lowmem_end_addr);
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}
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/* This is only called until mem_init is done. */
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void __init *early_get_page(void)
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{
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if (init_bootmem_done)
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return alloc_bootmem_pages(PAGE_SIZE);
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else
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return __va(memblock_alloc(PAGE_SIZE, PAGE_SIZE));
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}
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#ifdef CONFIG_8xx /* No 8xx specific .c file to put that in ... */
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void setup_initial_memory_limit(phys_addr_t first_memblock_base,
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phys_addr_t first_memblock_size)
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{
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/* We don't currently support the first MEMBLOCK not mapping 0
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* physical on those processors
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*/
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BUG_ON(first_memblock_base != 0);
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/* 8xx can only access 8MB at the moment */
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memblock_set_current_limit(min_t(u64, first_memblock_size, 0x00800000));
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}
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#endif /* CONFIG_8xx */
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