linux-kernel - [Part1 PATCH v5 03/22] x86, ACPI, mm: Kill max_low_pfn

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Date:	Thu, 13 Jun 2013 21:02:50 +0800
From:	Tang Chen <tangchen@...fujitsu.com>
To:	tglx@...utronix.de, mingo@...e.hu, hpa@...or.com,
	akpm@...ux-foundation.org, tj@...nel.org, trenn@...e.de,
	yinghai@...nel.org, jiang.liu@...wei.com, wency@...fujitsu.com,
	laijs@...fujitsu.com, isimatu.yasuaki@...fujitsu.com,
	mgorman@...e.de, minchan@...nel.org, mina86@...a86.com,
	gong.chen@...ux.intel.com, vasilis.liaskovitis@...fitbricks.com,
	lwoodman@...hat.com, riel@...hat.com, jweiner@...hat.com,
	prarit@...hat.com
Cc:	x86@...nel.org, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	"Rafael J. Wysocki" <rjw@...k.pl>, Jacob Shin <jacob.shin@....com>,
	Pekka Enberg <penberg@...nel.org>, linux-acpi@...r.kernel.org
Subject: [Part1 PATCH v5 03/22] x86, ACPI, mm: Kill max_low_pfn_mapped

From: Yinghai Lu <yinghai@...nel.org>

Now we have pfn_mapped[] array, and max_low_pfn_mapped should not
be used anymore. Users should use pfn_mapped[] or just
1UL<<(32-PAGE_SHIFT) instead.

The only user of max_low_pfn_mapped is ACPI_INITRD_TABLE_OVERRIDE.
We could change to use 1U<<(32_PAGE_SHIFT) with it, aka under 4G.

Known problem:
There is another user of max_low_pfn_mapped: i915 device driver.
But the code is commented out by a pair of "#if 0 ... #endif".
Not sure why the driver developers want to do that.

-v2: Leave alone max_low_pfn_mapped in i915 code according to tj.

Suggested-by: H. Peter Anvin <hpa@...or.com>
Signed-off-by: Yinghai Lu <yinghai@...nel.org>
Cc: "Rafael J. Wysocki" <rjw@...k.pl>
Cc: Jacob Shin <jacob.shin@....com>
Cc: Pekka Enberg <penberg@...nel.org>
Cc: linux-acpi@...r.kernel.org
Tested-by: Thomas Renninger <trenn@...e.de>
Reviewed-by: Tang Chen <tangchen@...fujitsu.com>
Tested-by: Tang Chen <tangchen@...fujitsu.com>
---
 arch/x86/include/asm/page_types.h |    1 -
 arch/x86/kernel/setup.c           |    4 +---
 arch/x86/mm/init.c                |    4 ----
 drivers/acpi/osl.c                |    6 +++---
 4 files changed, 4 insertions(+), 11 deletions(-)

diff --git a/arch/x86/include/asm/page_types.h b/arch/x86/include/asm/page_types.h
index 54c9787..b012b82 100644
--- a/arch/x86/include/asm/page_types.h
+++ b/arch/x86/include/asm/page_types.h
@@ -43,7 +43,6 @@
 
 extern int devmem_is_allowed(unsigned long pagenr);
 
-extern unsigned long max_low_pfn_mapped;
 extern unsigned long max_pfn_mapped;
 
 static inline phys_addr_t get_max_mapped(void)
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 66ab495..6ca5f2c 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -112,13 +112,11 @@
 #include <asm/prom.h>
 
 /*
- * max_low_pfn_mapped: highest direct mapped pfn under 4GB
- * max_pfn_mapped:     highest direct mapped pfn over 4GB
+ * max_pfn_mapped:     highest direct mapped pfn
  *
  * The direct mapping only covers E820_RAM regions, so the ranges and gaps are
  * represented by pfn_mapped
  */
-unsigned long max_low_pfn_mapped;
 unsigned long max_pfn_mapped;
 
 #ifdef CONFIG_DMI
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index eaac174..8554656 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -313,10 +313,6 @@ static void add_pfn_range_mapped(unsigned long start_pfn, unsigned long end_pfn)
 	nr_pfn_mapped = clean_sort_range(pfn_mapped, E820_X_MAX);
 
 	max_pfn_mapped = max(max_pfn_mapped, end_pfn);
-
-	if (start_pfn < (1UL<<(32-PAGE_SHIFT)))
-		max_low_pfn_mapped = max(max_low_pfn_mapped,
-					 min(end_pfn, 1UL<<(32-PAGE_SHIFT)));
 }
 
 bool pfn_range_is_mapped(unsigned long start_pfn, unsigned long end_pfn)
diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index e721863..93e3194 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -624,9 +624,9 @@ void __init acpi_initrd_override(void *data, size_t size)
 	if (table_nr == 0)
 		return;
 
-	acpi_tables_addr =
-		memblock_find_in_range(0, max_low_pfn_mapped << PAGE_SHIFT,
-				       all_tables_size, PAGE_SIZE);
+	/* under 4G at first, then above 4G */
+	acpi_tables_addr = memblock_find_in_range(0, (1ULL<<32) - 1,
+					all_tables_size, PAGE_SIZE);
 	if (!acpi_tables_addr) {
 		WARN_ON(1);
 		return;
-- 
1.7.1

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