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Date:      Mon, 21 Dec 2015 17:15:04 +0000 (UTC)
From:      Dimitry Andric <dim@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-10@freebsd.org
Subject:   svn commit: r292551 - stable/10/sys/amd64/amd64
Message-ID:  <201512211715.tBLHF4Oo031067@repo.freebsd.org>
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Author: dim
Date: Mon Dec 21 17:15:03 2015
New Revision: 292551
URL: https://svnweb.freebsd.org/changeset/base/292551

Log:
  MFC r277735 (by royger):
  
  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:
  stable/10/sys/amd64/amd64/machdep.c
Directory Properties:
  stable/10/   (props changed)

Modified: stable/10/sys/amd64/amd64/machdep.c
==============================================================================
--- stable/10/sys/amd64/amd64/machdep.c	Mon Dec 21 16:55:36 2015	(r292550)
+++ stable/10/sys/amd64/amd64/machdep.c	Mon Dec 21 17:15:03 2015	(r292551)
@@ -1344,8 +1344,10 @@ 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]) {
@@ -1383,7 +1385,7 @@ 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];
 	}
@@ -1548,7 +1550,6 @@ getmemsize(caddr_t kmdp, u_int64_t first
 	int page_counter;
 
 	bzero(physmap, sizeof(physmap));
-	basemem = 0;
 	physmap_idx = 0;
 
 	efihdr = (struct efi_map_header *)preload_search_info(kmdp,
@@ -1566,21 +1567,29 @@ getmemsize(caddr_t kmdp, u_int64_t first
 		panic("No BIOS smap or EFI map info from loader!");
 	}
 
+	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;
+	}
 
 #ifdef SMP
 	/* make hole for AP bootstrap code */
+	if (physmap[1] >= 0x100000000)
+		panic("Basemem segment is not suitable for AP bootstrap code!");
 	physmap[1] = mp_bootaddress(physmap[1] / 1024);
 #endif
 
@@ -1634,12 +1643,14 @@ 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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