amd64/138220: [patch] FreeBSD/amd64 can't see all system memory

[James R. Van Artsdalen]

>Number:         138220
>Category:       amd64
>Synopsis:       [patch] FreeBSD/amd64 can't see all system memory
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    freebsd-amd64
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Wed Aug 26 23:00:08 UTC 2009
>Closed-Date:
>Last-Modified:
>Originator:     James R. Van Artsdalen
>Release:        FreeBSD 9.0-CURRENT amd64
>Organization:
>Environment:
System: FreeBSD pygmy.housenet.jrv 9.0-CURRENT FreeBSD 9.0-CURRENT #1 r196500M: Wed Aug 26 11:28:43 CDT 2009 james at pygmy.housenet.jrv:/usr/src/sys/amd64/compile/GENERIC amd64


>Description:

Two related bugs:

1. FreeBSD erroneously assumes that the BIOS E820 system memory map data
is non-descending.  The Zotac GF9300-D-E is an example of a system where
this is not true.

2. There is a typo in code that detects overlaps in regions reported by
E820.  No action is in fact taken right now on amd64.

i386 may have bug #1 but not #2.

With this patch "available memory" goes from 2689 MB to 7605 MB on the
Zotac GF9300-D-E.



>How-To-Repeat:
Boot amd64 on Zotac GF9300-D-E motherboard with 8GB of RAM.  Less than 3GB is reported.

>Fix:

No user fix.

The patch sorts smap enteries on the base address and ignores overlapping regions.

--- smap.pat begins here ---
Index: sys/amd64/amd64/machdep.c
===================================================================
--- sys/amd64/amd64/machdep.c	(revision 196500)
+++ sys/amd64/amd64/machdep.c	(working copy)
@@ -1236,6 +1236,19 @@
 	smapend = (struct bios_smap *)((uintptr_t)smapbase + smapsize);
 
 	for (smap = smapbase; smap < smapend; smap++) {
+		struct bios_smap *sp, *low = smap;
+
+		for (sp = smap + 1; sp < smapend; sp++)
+			if (low->base > sp->base)
+				low = sp;
+		if (low != smap) {
+			struct bios_smap ts;
+
+			ts = *smap;
+			*smap = *low;
+			*low = ts;
+		}
+
 		if (boothowto & RB_VERBOSE)
 			printf("SMAP type=%02x base=%016lx len=%016lx\n",
 			    smap->type, smap->base, smap->length);
@@ -1250,10 +1263,12 @@
 			if (smap->base < physmap[i + 1]) {
 				if (boothowto & RB_VERBOSE)
 					printf(
-	"Overlapping or non-monotonic memory region, ignoring second region\n");
-				continue;
+	"Overlapping memory region, ignoring second region\n");
+				break;
 			}
 		}
+		if (i <= physmap_idx)
+		  continue;
 
 		if (smap->base == physmap[physmap_idx + 1]) {
 			physmap[physmap_idx + 1] += smap->length;
--- smap.pat ends here ---


>Release-Note:
>Audit-Trail:
>Unformatted: