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Date:      Mon, 26 Jan 2015 08:42:48 +0000 (UTC)
From:      Roger Pau Monné <royger@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r277735 - head/sys/amd64/amd64
Message-ID:  <201501260842.t0Q8gmhL014666@svn.freebsd.org>
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Author: royger
Date: Mon Jan 26 08:42:47 2015
New Revision: 277735
URL: https://svnweb.freebsd.org/changeset/base/277735

Log:
  amd64: allow base memory segment to start at address different than 0
  
  Current code requires that the first physical memory segment starts at 0,
  but this is not really needed. We only need to make sure the bootstrap code
  and page tables for APs are allocated below 4GB.
  
  This patch removes this requirement and allows booting a Dell R710 from
  UEFI, where the first physical memory segment starts at 0x10000.
  
  Sponsored by: Citrix Systems R&D
  Reviewed by: jhb
  Differential Revision: https://reviews.freebsd.org/D1417

Modified:
  head/sys/amd64/amd64/machdep.c

Modified: head/sys/amd64/amd64/machdep.c
==============================================================================
--- head/sys/amd64/amd64/machdep.c	Mon Jan 26 08:30:24 2015	(r277734)
+++ head/sys/amd64/amd64/machdep.c	Mon Jan 26 08:42:47 2015	(r277735)
@@ -1355,8 +1355,10 @@ add_physmap_entry(uint64_t base, uint64_
 	/*
 	 * Find insertion point while checking for overlap.  Start off by
 	 * assuming the new entry will be added to the end.
+	 *
+	 * NB: physmap_idx points to the next free slot.
 	 */
-	insert_idx = physmap_idx + 2;
+	insert_idx = physmap_idx;
 	for (i = 0; i <= physmap_idx; i += 2) {
 		if (base < physmap[i + 1]) {
 			if (base + length <= physmap[i]) {
@@ -1394,7 +1396,7 @@ add_physmap_entry(uint64_t base, uint64_
 	 * Move the last 'N' entries down to make room for the new
 	 * entry if needed.
 	 */
-	for (i = physmap_idx; i > insert_idx; i -= 2) {
+	for (i = (physmap_idx - 2); i > insert_idx; i -= 2) {
 		physmap[i] = physmap[i - 2];
 		physmap[i + 1] = physmap[i - 1];
 	}
@@ -1580,23 +1582,27 @@ getmemsize(caddr_t kmdp, u_int64_t first
 	int page_counter;
 
 	bzero(physmap, sizeof(physmap));
-	basemem = 0;
 	physmap_idx = 0;
 
 	init_ops.parse_memmap(kmdp, physmap, &physmap_idx);
+	physmap_idx -= 2;
 
 	/*
 	 * Find the 'base memory' segment for SMP
 	 */
 	basemem = 0;
 	for (i = 0; i <= physmap_idx; i += 2) {
-		if (physmap[i] == 0x00000000) {
+		if (physmap[i] <= 0xA0000) {
 			basemem = physmap[i + 1] / 1024;
 			break;
 		}
 	}
-	if (basemem == 0)
-		panic("BIOS smap did not include a basemem segment!");
+	if (basemem == 0 || basemem > 640) {
+		if (bootverbose)
+			printf(
+		"Memory map doesn't contain a basemem segment, faking it");
+		basemem = 640;
+	}
 
 	/*
 	 * Make hole for "AP -> long mode" bootstrap code.  The
@@ -1604,8 +1610,12 @@ getmemsize(caddr_t kmdp, u_int64_t first
 	 * is configured to support APs and APs for the system start
 	 * in 32bit mode (e.g. SMP bare metal).
 	 */
-	if (init_ops.mp_bootaddress)
+	if (init_ops.mp_bootaddress) {
+		if (physmap[1] >= 0x100000000)
+			panic(
+	"Basemem segment is not suitable for AP bootstrap code!");
 		physmap[1] = init_ops.mp_bootaddress(physmap[1] / 1024);
+	}
 
 	/*
 	 * Maxmem isn't the "maximum memory", it's one larger than the
@@ -1657,12 +1667,14 @@ getmemsize(caddr_t kmdp, u_int64_t first
 	 */
 	physmem_start = (vm_guest > VM_GUEST_NO ? 1 : 16) << PAGE_SHIFT;
 	TUNABLE_ULONG_FETCH("hw.physmem.start", &physmem_start);
-	if (physmem_start < PAGE_SIZE)
-		physmap[0] = PAGE_SIZE;
-	else if (physmem_start >= physmap[1])
-		physmap[0] = round_page(physmap[1] - PAGE_SIZE);
-	else
-		physmap[0] = round_page(physmem_start);
+	if (physmap[0] < physmem_start) {
+		if (physmem_start < PAGE_SIZE)
+			physmap[0] = PAGE_SIZE;
+		else if (physmem_start >= physmap[1])
+			physmap[0] = round_page(physmap[1] - PAGE_SIZE);
+		else
+			physmap[0] = round_page(physmem_start);
+	}
 	pa_indx = 0;
 	da_indx = 1;
 	phys_avail[pa_indx++] = physmap[0];

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