@being html@
Functions for Memory Initialization

machine_specific_memory_setup()


static char * __init machine_specific_memory_setup(void)
{
	char *who;

who = "BIOS-e820";

/* * Try to copy the BIOS-supplied E820-map. * * Otherwise fake a memory map; one section from 0k->640k, * the next section from 1mb->appropriate_mem_k */ sanitize_e820_map(E820_MAP, &E820_MAP_NR); if (copy_e820_map(E820_MAP, E820_MAP_NR) < 0) { unsigned long mem_size;

/* compare results from other methods and take the greater */ if (ALT_MEM_K < EXT_MEM_K) { mem_size = EXT_MEM_K; who = "BIOS-88"; } else { mem_size = ALT_MEM_K; who = "BIOS-e801"; }

e820.nr_map = 0; add_memory_region(0, LOWMEMSIZE(), E820_RAM); add_memory_region(HIGH_MEMORY, mem_size << 10, E820_RAM); } return who; }

sanitize_e820_map()


static int __init sanitize_e820_map(struct e820entry * biosmap, char * pnr_map)
{
	struct change_member *change_tmp;
	unsigned long current_type, last_type;
	unsigned long long last_addr;
	int chgidx, still_changing;
	int overlap_entries;
	int new_bios_entry;
	int old_nr, new_nr, chg_nr;
	int i;

/* Visually we're performing the following (1,2,3,4 = memory types)...

Sample memory map (w/overlaps): ____22__________________ ______________________4_ ____1111________________ _44_____________________ 11111111________________ ____________________33__ ___________44___________ __________33333_________ ______________22________ ___________________2222_ _________111111111______ _____________________11_ _________________4______

Sanitized equivalent (no overlap): 1_______________________ _44_____________________ ___1____________________ ____22__________________ ______11________________ _________1______________ __________3_____________ ___________44___________ _____________33_________ _______________2________ ________________1_______ _________________4______ ___________________2____ ____________________33__ ______________________4_ */

/* if there's only one memory region, don't bother */ if (*pnr_map < 2) return -1;

old_nr = *pnr_map;

/* bail out if we find any unreasonable addresses in bios map */ for (i=0; i<old_nr; i++) if (biosmap[i].addr + biosmap[i].size < biosmap[i].addr) return -1;

/* create pointers for initial change-point information (for sorting) */ for (i=0; i < 2*old_nr; i++) change_point[i] = &change_point_list[i];

/* record all known change-points (starting and ending addresses), omitting those that are for empty memory regions */ chgidx = 0; for (i=0; i < old_nr; i++) { if (biosmap[i].size != 0) { change_point[chgidx]->addr = biosmap[i].addr; change_point[chgidx++]->pbios = &biosmap[i]; change_point[chgidx]->addr = biosmap[i].addr + biosmap[i].size; change_point[chgidx++]->pbios = &biosmap[i]; } } chg_nr = chgidx; /* true number of change-points */

/* sort change-point list by memory addresses (low -> high) */ still_changing = 1; while (still_changing) { still_changing = 0; for (i=1; i < chg_nr; i++) { /* if <current_addr> > <last_addr>, swap */ /* or, if current=<start_addr> & last=<end_addr>, swap */ if ((change_point[i]->addr < change_point[i-1]->addr) || ((change_point[i]->addr == change_point[i-1]->addr) && (change_point[i]->addr == change_point[i]->pbios->addr) && (change_point[i-1]->addr != change_point[i-1]->pbios->addr)) ) { change_tmp = change_point[i]; change_point[i] = change_point[i-1]; change_point[i-1] = change_tmp; still_changing=1; } } }

/* create a new bios memory map, removing overlaps */ overlap_entries=0; /* number of entries in the overlap table */ new_bios_entry=0; /* index for creating new bios map entries */ last_type = 0; /* start with undefined memory type */ last_addr = 0; /* start with 0 as last starting address */ /* loop through change-points, determining affect on the new bios map */ for (chgidx=0; chgidx < chg_nr; chgidx++) { /* keep track of all overlapping bios entries */ if (change_point[chgidx]->addr == change_point[chgidx]->pbios->addr) { /* add map entry to overlap list (> 1 entry implies an overlap) */ overlap_list[overlap_entries++]=change_point[chgidx]->pbios; } else { /* remove entry from list (order independent, so swap with last) */ for (i=0; i<overlap_entries; i++) { if (overlap_list[i] == change_point[chgidx]->pbios) overlap_list[i] = overlap_list[overlap_entries-1]; } overlap_entries--; } /* if there are overlapping entries, decide which "type" to use */ /* (larger value takes precedence -- 1=usable, 2,3,4,4+=unusable) */ current_type = 0; for (i=0; i<overlap_entries; i++) if (overlap_list[i]->type > current_type) current_type = overlap_list[i]->type; /* continue building up new bios map based on this information */ if (current_type != last_type) { if (last_type != 0) { new_bios[new_bios_entry].size = change_point[chgidx]->addr - last_addr; /* move forward only if the new size was non-zero */ if (new_bios[new_bios_entry].size != 0) if (++new_bios_entry >= E820MAX) break; /* no more space left for new bios entries */ } if (current_type != 0) { new_bios[new_bios_entry].addr = change_point[chgidx]->addr; new_bios[new_bios_entry].type = current_type; last_addr=change_point[chgidx]->addr; } last_type = current_type; } } new_nr = new_bios_entry; /* retain count for new bios entries */

/* copy new bios mapping into original location */ memcpy(biosmap, new_bios, new_nr*sizeof(struct e820entry)); *pnr_map = new_nr;

return 0; }

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