I spent some time testing the previous patch today. I found a couple of corner cases
that weren't handled correctly in the first version.
I've attached a new version (against 2.4.2-ac7) that should fix those problems.
Brian
[EMAIL PROTECTED]
--- linux-2.4.2-ac7/arch/i386/kernel/setup.c Thu Mar 1 15:39:08 2001
+++ linux/arch/i386/kernel/setup.c Thu Mar 1 15:59:06 2001
@@ -58,6 +58,9 @@
* Massive cleanup of CPU detection and bug handling;
* Transmeta CPU detection,
* H. Peter Anvin <[EMAIL PROTECTED]>, November 2000
+ *
+ * Added E820 sanitization routine (removes overlapping memory regions);
+ * Brian Moyle <[EMAIL PROTECTED]>, February 2001
*/
/*
@@ -438,6 +441,170 @@
}
/*
+ * Sanitize the BIOS e820 map.
+ *
+ * Some e820 responses include overlapping entries. The following
+ * replaces the original e820 map with a new one, removing overlaps.
+ *
+ */
+static int __init sanitize_e820_map(struct e820entry * biosmap, char * pnr_map)
+{
+ struct change_member {
+ struct e820entry *pbios; /* pointer to original bios entry */
+ unsigned long long addr; /* address for this change point */
+ };
+ struct change_member change_point_list[2*E820MAX];
+ struct change_member *change_point[2*E820MAX];
+ struct e820entry *overlap_list[E820MAX];
+ struct e820entry new_bios[E820MAX];
+ 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;
+ 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) */
+ chgidx = 0;
+ for (i=0; i < old_nr; i++) {
+ 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];
+ }
+
+ /* sort change-point list by memory addresses (low -> high) */
+ still_changing = 1;
+ while (still_changing) {
+ still_changing = 0;
+ for (i=1; i < 2*old_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 < 2*old_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;
+}
+
+/*
* Copy the BIOS e820 map into a safe place.
*
* Sanity-check it while we're at it..
@@ -504,6 +671,7 @@
* 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;
