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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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ac71d12c99
Based on analysis&patch from Robert Hentosch Observed on a Dell PE6850 with 16GB The problem occurs very early on, when the kernel allocates space for the temporary memory map called bootmap. The bootmap overlaps the EBDA region. EBDA region is not historically reserved in the e820 mapping. When the bootmap is freed it marks the EBDA region as usable. If you notice in setup.c there is already code to work around the EBDA in reserve_ebda_region(), this check however occurs after the bootmap is allocated and doesn't prevent the bootmap from using this range. AK: I redid the original patch. Thanks also to Jan Beulich for spotting some mistakes. Cc: Robert_Hentosch@dell.com Cc: jbeulich@novell.com Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
67 lines
2.0 KiB
C
67 lines
2.0 KiB
C
/*
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* structures and definitions for the int 15, ax=e820 memory map
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* scheme.
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*
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* In a nutshell, setup.S populates a scratch table in the
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* empty_zero_block that contains a list of usable address/size
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* duples. setup.c, this information is transferred into the e820map,
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* and in init.c/numa.c, that new information is used to mark pages
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* reserved or not.
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*/
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#ifndef __E820_HEADER
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#define __E820_HEADER
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#include <linux/mmzone.h>
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#define E820MAP 0x2d0 /* our map */
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#define E820MAX 128 /* number of entries in E820MAP */
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#define E820NR 0x1e8 /* # entries in E820MAP */
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#define E820_RAM 1
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#define E820_RESERVED 2
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#define E820_ACPI 3 /* usable as RAM once ACPI tables have been read */
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#define E820_NVS 4
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#define HIGH_MEMORY (1024*1024)
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#define LOWMEMSIZE() (0x9f000)
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#ifndef __ASSEMBLY__
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struct e820entry {
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u64 addr; /* start of memory segment */
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u64 size; /* size of memory segment */
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u32 type; /* type of memory segment */
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} __attribute__((packed));
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struct e820map {
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int nr_map;
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struct e820entry map[E820MAX];
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};
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extern unsigned long find_e820_area(unsigned long start, unsigned long end,
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unsigned size);
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extern void add_memory_region(unsigned long start, unsigned long size,
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int type);
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extern void setup_memory_region(void);
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extern void contig_e820_setup(void);
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extern unsigned long e820_end_of_ram(void);
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extern void e820_reserve_resources(void);
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extern void e820_print_map(char *who);
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extern int e820_any_mapped(unsigned long start, unsigned long end, unsigned type);
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extern int e820_all_mapped(unsigned long start, unsigned long end, unsigned type);
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extern void e820_bootmem_free(pg_data_t *pgdat, unsigned long start,unsigned long end);
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extern void e820_setup_gap(void);
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extern unsigned long e820_hole_size(unsigned long start_pfn,
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unsigned long end_pfn);
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extern void __init parse_memopt(char *p, char **end);
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extern void __init parse_memmapopt(char *p, char **end);
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extern struct e820map e820;
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extern unsigned ebda_addr, ebda_size;
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#endif/*!__ASSEMBLY__*/
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#endif/*__E820_HEADER*/
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